# CUCM to Webex Calling migration

Systems: Cisco Unified Communications Manager to Webex Calling

For Collaboration administrators running Unified CM and holding full Control Hub administrator privileges.

Canonical: https://warmtransfer.net/guides/cucm-to-webex-calling

Last verified: 2026-09-22

Cisco organises the transition from Cisco Unified Communications Manager to Webex Calling into 5 sequential phases named Prepare, Plan, Design, Implement, and Optimize[^67]. The last date of support for Version 14 perpetual on-premises calling applications is 30 April 2027, after which Cisco states all support services are unavailable and the product is obsolete[^8].

## Before you start

The data migration flow lists an active Webex Calling subscription with entitlement PID A-FLEX-P-CALL as a prerequisite, alongside organisation administrator access to Control Hub[^19]. All Unified CM end users must already be provisioned as Webex users, through Cisco Directory Connector or another mechanism, before the migration task runs[^112]. Phones on Unified CM that are being migrated must run Phone Load version 14.1 or later[^111]. Only the Cisco 6800, 7800, 8800, and 9800 desk phone series are supported with Webex Calling, representing a subset of the phones supported on Unified CM[^85]. The recommended project lifecycle runs across 3 phases: Pre-Migration, Migration Prep, and Migration Rollout and Decommission[^121].

## What changes by situation

- Do all users and devices move in one window, or in groups over time? Flash-cut: everything moves in a single migration window; Phased: groups move over an extended period with both platforms live.
- How does each migrating location reach the public network? Cloud PSTN everywhere: Cisco Calling Plan or Cloud Connected PSTN; Local Gateway everywhere: on-premises PSTN via CUBE or third-party SBC; Mixed: some locations on cloud PSTN, others on Local Gateway.
- What has to happen to the desk phones before they can register to Webex Calling? 9800 series on PhoneOS: registers to both platforms without firmware change; 7800/8800 series on Enterprise firmware: convert to Multiplatform firmware; 6800 series on Enterprise firmware, or end-of-sale models: replace hardware.
- Does the estate use call park or call pickup groups? No call park or call pickup groups in scope; Call park and/or call pickup groups are in use and must be rebuilt.

## Step 1: Assess the estate with Migration Insights

### Do
Access Migration Insights in Control Hub under Services, then Updates and Migrations, and open the card with View[^56]. Sources disagree on the menu label, with one help article indicating Services then Upgrades and Migrations while another specifies Services then Updates and Migrations[^99]. Upload a Unified CM `.tar` export extracted with the Bulk Administration Tool of at most 350 MB, and optionally attach a `.gzip` file of call detail record data of at most 2 GB[^58]. Use feature assessment comprising static configuration from Migration Insights alongside dynamic utilisation from call detail records, registrations, and call activity[^71]. Assess licensing, locations and sites, device inventory and eligibility, users, PSTN connectivity, features and feature usage, Cisco integrations including Unity Connection, call recording, and third-party integrations[^68].

### Verify
Export the assessment `.zip` and confirm receipt of the output reports, specifically `DeviceEligibility.csv`, `HuntGroupCallQueueCallParkCallPickUpGroups.csv`, `sharedlineGroupmigrationreport.csv`, `FeatureUsageBasedDeviceEligibilityReport.csv`, `DidUsageReport.csv`, `UserWorksapceLastUsage.csv`, and `ImportedDataBulk.csv`[^57].

### Rollback
Suggested rollback: Remove the exported assessment archive and uploaded data from the local workstation. Cisco lists business reasons to retain call control on premises, including unsupported phone models, complex integrations lacking cloud equivalents, complex dial plans, granular classes of service, unreliable internet access, strict data privacy, in-country call recording mandates, and contact-centre integrations[^113].

## Step 2: Connect the cluster with Cloud-Connected UC

### Do
Deploy Cloud-Connected UC early in the transition project during the preparation phase[^69]. For Unified CM Release 12.5(1)SU2 and later, run `utils ucmgmt organization <organization_id>` followed by `utils ucmgmt agent enable` on the admin CLI to onboard the node via the built-in agent code[^12][^13]. Where the built-in agent is not available, create an Agent Cisco Operations Package COP file in Control Hub with necessary proxy settings, and install it across all nodes in the cluster[^14].

### Verify
Verify onboarding by matching the verification code displayed in the node installation logs and sign-in pages against the code displayed in Control Hub before assigning the node to a cluster group[^16].

### Rollback
Suggested rollback: Disable the management agent on the administrative CLI. WarmTransfer's reading of the sources is that Cloud-Connected UC gates automated migration paths, meaning disabling it prevents CDR-based usage reporting and in-Control-Hub firmware migration, requiring manual BAT file exchanges for device changes[^15].

## Step 3: Prove network readiness

### Do
Open the enterprise firewall to allow outbound SIP, RTP over UDP, and HTTP to documented Webex Calling addresses and ports[^61]. Align network performance to Cisco targets for voice quality over the internet: 1-way latency below 100 milliseconds, jitter below 10 milliseconds, and packet loss of 0.5 percent or less[^124]. Select the Webex Calling instance providing the lowest signalling round-trip times for the largest user base, noting that the region assignment cannot easily be modified later[^30][^127].

### Verify
Suggested check: Test latency, jitter, and packet loss against the recommended thresholds across all local campus network segments.

### Rollback
Suggested rollback: Revert firewall configuration changes permitting outbound media and signalling ports.

## Step 4: Stand up the PSTN edge

**Cloud PSTN everywhere: Cisco Calling Plan or Cloud Connected PSTN**

### Do
Order PSTN connectivity through Cisco Calling Plans or Cloud Connected PSTN providers prior to configuring calling locations[^29][^52]. Cloud PSTN provides PSTN access exclusively for Webex Calling users; premises users cannot route outbound calls to cloud PSTN through this path[^77].

### Verify
Suggested check: Place test inbound and outbound public telephone calls using an unassigned test number configured on the cloud subscription.

### Rollback
Delete unassigned telephone numbers in Control Hub, noting that numbers assigned to users, workspaces, or features cannot be deleted[^64].

**Local Gateway everywhere: on-premises PSTN via CUBE or third-party SBC**

### Do
Deploy a Local Gateway on supported hardware equipped with CUBE calling licences, a CA root bundle, and SIP digest credentials retrieved from Control Hub[^61]. For capacities up to 250 concurrent calls per trunk, deploy registration-based trunks with Cisco CUBE using digest authentication; deploy certificate-based trunks when exceeding 250 concurrent calls per trunk[^59]. Certificate-based trunking is supported on Cisco CUBE starting from Cisco IOS XE Cupertino 17.9.1a, Cisco Secure Routers, Oracle, AudioCodes Mediant, Ribbon, anynode, and Italtel NetMatch-S[^60].

### Verify
Suggested check: Confirm SIP trunk registration and establish test inbound and outbound calls through the gateway.

### Rollback
Suggested rollback: Remove the gateway dial peers, clear digest credentials, and delete the trunk entry from Control Hub.

**Mixed: some locations on cloud PSTN, others on Local Gateway**

### Do
Procure cloud PSTN via Cisco Calling Plans or Cloud Connected PSTN for designated cloud sites, and deploy Local Gateways on supported platforms with CUBE calling licences, CA bundles, and digest credentials for on-premises sites[^29][^61]. For Local Gateway deployments exceeding 250 concurrent calls per trunk, use certificate-based trunking[^59]. The Local Gateway can simultaneously provide PSTN access and an interconnect to on-premises call control during coexistence[^94]. Do not assume cloud PSTN can serve premises users, as cloud PSTN routes calls only for Webex Calling users[^77].

### Verify
Suggested check: Place test calls through both the cloud PSTN and Local Gateway connections to verify bidirectional connectivity across all site types.

### Rollback
Suggested rollback: Decommission configured trunks and remove unassigned numbers from Control Hub[^64].

## Step 5: Provision locations, numbers, and emergency calling

### Do
Document each location with extension ranges, DID ranges, PSTN steering digits, site code, main number, voicemail number, licence counts, busy-hour concurrent calls, country, time zone, language, contact details, address, and emergency dispatchable location[^28]. Note that extension length in Webex Calling is a fixed global setting across the entire deployment[^26]. Add numbers under Services, PSTN and Routing, Numbers by choosing Manage then Add, importing up to 1000 numbers at a time in E.164 format (or national format within the United States)[^63]. Mark numbers awaiting carrier porting with Activate Numbers Later[^62]. For United States and Canada locations, provide a valid street address for platform validation to generate PIDF-LO location data for emergency calls[^55]. The Webex Calling E911 service is documented as addressing RAY BAUM'S Act Phase 2, effective January 2022, and Kari's Law[^35]. Enable Enhanced Emergency Calling in Control Hub by entering a HELD Company ID and Secret Key from RedSky, toggling the feature on, and configuring network wiremap data including wireless access point MAC addresses, LLDP switch data, and IP subnets[^34][^36].

### Verify
Verify emergency call configuration by dialling 933 from each location before enabling live 911 routing, confirming caller ID and address readback from the IVR[^33].

### Rollback
Delete unassigned numbers in Control Hub, noting that numbers assigned to active entities cannot be deleted[^64].

## Step 6: Synchronise identity and assign user licences

### Do
Provision users into Webex using manual assignment in Control Hub, automatic licence templates, bulk CSV upload, or API assignment[^27]. Implement single sign-on using SAML 2.0, OpenID Connect, or Webex identity[^31]. For users moving via the migration tool, assign Calling Professional or CX Essentials licences[^74]. For workspaces, assign Workspace or Professional Workspace licences[^75]. If assigning Webex Calling Standard licences, use the user CSV import path paired with the Migrate features from the Unified CM tool rather than the data migration tool[^73].

### Verify
Verify that all migrating users and phone numbers exist in Control Hub in the correct format prior to batch execution[^51]. Confirm that Unified CM email IDs match Webex identities, as email ID is used to match users during number assignment[^25].

### Rollback
Suggested rollback: Remove calling licences from provisioned user accounts in Control Hub.

## Step 7: Define batches and migration scope

**Flash-cut: everything moves in a single migration window**

### Do
Schedule a single cutover window to move all users and devices, after which on-premises call control will be decommissioned[^96]. WarmTransfer's reading of the sources is that because a single migration task caps at 1000 users and 1000 devices, a flash-cut of an estate larger than that is not one task but several tasks run inside one cutover window, which sets a practical floor on how long the window can be[^120][^39]. Cap firmware migration tasks at 1000 devices per task[^44].

### Verify
Suggested check: Review task queues in Control Hub to confirm total user and device counts across scheduled tasks match inventory.

### Rollback
WarmTransfer's reading of the sources is that neither the data migration nor the firmware migration documents an automated rollback procedure, so backout depends on maintaining the Unified CM cluster operational and redirecting devices back to on-premises call control[^22][^42][^66].

**Phased: groups move over an extended period with both platforms live**

### Do
Structure the rollout into batches spanning an extended coexistence window where both Unified CM and Webex Calling operate simultaneously[^96][^97]. The phased architecture runs from Phase 0 with Unified CM only on premises through Phase 1 hybrid coexistence[^97]. Group feature members who must move in the same batch are identified by BLF monitoring relationships, membership of hunt pilots or call queues, shared lines, call pickup groups, intercom, and executive and administrative assistant pairings[^48]. Restrict each migration task batch to a maximum of 1000 users and 1000 devices[^120].

### Verify
Cross-reference batch lists against `sharedlineGroupmigrationreport.csv` and `HuntGroupCallQueueCallParkCallPickUpGroups.csv` to ensure no group feature members are divided across batches[^57]. Complete pre-batch validation checks for phone number formatting and licence templates[^51].

### Rollback
Cisco explicitly supports organisations choosing to remain indefinitely in the Phase 1 dual call control coexistence state without completing full cloud transition[^97][^105].

## Step 8: Configure interconnect trunks and dial plan

**Flash-cut: everything moves in a single migration window**

### Do
Establish the interconnect before cutover by configuring trunks, route groups, enterprise dial plans, and location and global call routing settings between Webex Calling and Unified CM[^53][^119]. WarmTransfer's reading of the sources is that retaining the interconnect and on-premises call control during cutover serves as the retreat path for the migration[^66].

### Verify
Suggested check: Place bidirectional test calls across the interconnect trunk using test extensions on Unified CM and Webex Calling.

### Rollback
Suggested rollback: Remove the interconnect trunk and enterprise route patterns from Control Hub.

**Phased: groups move over an extended period with both platforms live**

### Do
Configure trunks, route groups, enterprise dial plans, and location and global call routing settings[^53]. Configure the dial plan to route calls destined for Unified CM as enterprise calls and other destinations as PSTN calls across the trunk[^93]. In Cisco's documented coexistence configuration the Local Gateway separates traffic by port: calls arriving from Unified CM on port 5060 are routed to the PSTN and calls arriving on port 5065 are routed to Webex Calling, which requires setting the Unified CM SIP trunk security profile incoming port to 5065[^95]. On Unified CM, configure a single partition for +E.164 directory numbers with core routing on +E.164 route patterns[^32]. Enable unknown extension routing per location with a configured extension length between 2 and 10 digits to preserve abbreviated dialling to unmigrated premises extensions[^54][^92]. If routing to multiple distinct on-premises systems, configure multiple Webex Calling dial plans[^49].

### Verify
From a Webex Calling user, dial an unmigrated 4-digit extension to verify unknown extension routing redirects to Unified CM[^92]. From a Unified CM device, dial an on-net Webex Calling extension and an external number to confirm enterprise versus PSTN routing[^93].

### Rollback
Suggested rollback: Disable unknown extension routing on the calling location and remove the interconnect route group.

## Step 9: Prepare and transition desk phone endpoints

**9800 series on PhoneOS: registers to both platforms without firmware change**

### Do
Phones on Unified CM that are being migrated must be running Phone Load version 14.1 or later[^111]. The Cisco 9800 series runs PhoneOS, which supports registration to both Unified CM and Webex Calling, so 9800 phones transition without a firmware conversion[^82].

### Verify
Run the device eligibility check in Control Hub using Generate device license only to validate eligibility without creating device records, ensuring units return an Eligible status[^45][^100].

### Rollback
Suggested rollback: Keep the phones registered to the existing call control platform by maintaining existing device pool assignments.

**7800/8800 series on Enterprise firmware: convert to Multiplatform firmware**

### Do
Convert Cisco 7800 and 8800 series phones from Enterprise firmware to Multiplatform firmware before they can register to Webex Calling[^79]. Obtain migration licences generated via the Cisco web portal or host licences and firmware directly on Unified CM[^89][^90]. Note that hardware version floors apply: the 7821 and 7861 require hardware version V03 or later, the 7841 requires V04 or later, and the device must run software version 11.3.1MES5 or later[^128]. In Control Hub, create a firmware task capped at 1000 devices, choosing Generate device license and add device or Generate device license only[^46][^44]. With Cloud-Connected UC enabled, select the Unified CM TFTP load server and choose Migrate Phones to process devices in batches of 200[^40]. Without Cloud-Connected UC, download BAT files from Control Hub, upload them on Unified CM under Bulk Administration Upload/Download Files with Target Phone and Transaction Type Update Phone - Custom File, and confirm completion in Control Hub[^41]. Do not migrate 8845, 8865, or 8865NR video phones, as they are end-of-sale and Cisco advises against migrating them[^81], even though they are separately catalogued as supported personal video phones[^83]. Note that Older 8800 series units with hardware version VID 14 or earlier will register with Webex Calling but may show performance issues arising from hardware limitations[^80].

### Verify
Confirm that the Control Hub eligibility check marks devices as Eligible rather than Ineligible or Unknown[^45]. If Unknown devices appear, resolve them by inspecting the physical VID label or using the third-party IP Phone Readiness Tool[^123]. Note that Cisco states the IP Phone Readiness Tool is not an official Cisco tool, is not supported by Cisco TAC, and carries best-effort support only[^125].

### Rollback
WarmTransfer's reading of the sources is that because documentation describes no procedure for reverting a phone from Multiplatform firmware back to Enterprise firmware, conversion is an irreversible one-way operation for that physical device[^42].

**6800 series on Enterprise firmware, or end-of-sale models: replace hardware**

### Do
Procure replacement desk phones from the supported Cisco 6800, 7800, 8800, or 9800 series[^85]. Replace any Cisco 6800 series devices running Enterprise firmware, because 6800 Enterprise units cannot be converted to Multiplatform firmware[^78].

### Verify
Verify that replacement devices appear as Eligible in the Control Hub device eligibility tool using the Generate device license only check[^45][^100].

### Rollback
Suggested rollback: Retain disconnected legacy phones on-premises until replacement devices are commissioned.

## Step 10: Migrate clients to Webex App

### Do
Migrate active Jabber users to Webex App while their calling service remains registered to Unified CM[^114]. Webex App is the only soft client supported by Webex Calling, whereas Unified CM supports both Webex App and Jabber[^76].

### Verify
Suggested check: Place and receive calls on the soft client while the endpoint remains registered to call control.

### Rollback
Suggested rollback: Re-enable legacy soft client sign-in and user configurations on the call processing cluster.

## Step 11: Execute the data migration task

**Cloud PSTN everywhere: Cisco Calling Plan or Cloud Connected PSTN**

### Do
Navigate in Control Hub under Services, then Upgrades and Migrations, to the tile named Migrate Unified CM to Webex Calling[^101]. Under Step 2 Import data, click Action then Import user list and upload the Unified CM `.tar` archive[^20]. Use a CSV formatted with CUCM USER ID, EMAIL ID, DEVICE MAC, CUSTOM DEVICE POOL, and USER AREA CODE[^17]. Create a task with a unique name of at least 8 characters[^24]. Map device pools to Webex Calling locations and resolve multiple-location mapping warnings[^18]. Assign Calling Professional or CX Essentials licences to users and Workspace or Professional Workspace licences to workspaces[^74][^75]. Limit each task to 1000 users and 1000 devices[^120]. Numbers that will be ported later are added with the Activate Numbers Later option, staying inactive until activated[^62]. Click Prepare to Migrate to generate device profiles in Webex App[^23].

### Verify
Download the migration task reports at the Review step before selecting Prepare to Migrate, and verify all user numbers against directory source records[^23].

### Rollback
WarmTransfer's reading of the sources is that no reverse action exists for a completed data migration task in Control Hub, requiring administrators to rely on the parallel Unified CM environment[^22][^66].

**Local Gateway everywhere: on-premises PSTN via CUBE or third-party SBC**

### Do
Navigate in Control Hub to Services, Upgrades and Migrations, and select Migrate Unified CM to Webex Calling[^101]. Under Step 2 Import data, select Action, click Import user list, and upload the `.tar` export[^20]. Supply the CSV containing CUCM USER ID, EMAIL ID, DEVICE MAC, CUSTOM DEVICE POOL, and USER AREA CODE[^17]. Name the task with at least 8 characters[^24]. Map Unified CM device pools to locations[^18]. Assign Calling Professional or CX Essentials licences to users and Workspace or Professional Workspace licences to workspaces[^74][^75]. Limit the task to at most 1000 users and 1000 devices[^120]. Add numbers in Control Hub under Services, PSTN and Routing, Numbers by choosing Manage then Add, up to 1000 numbers at a time in E.164 format[^63]. Proceed to Review and click Prepare to Migrate[^23].

### Verify
Download and inspect the Review step reports, confirming every user maps to their assigned on-premises DID[^23].

### Rollback
WarmTransfer's reading of the sources is that because no backout tool exists for completed data migration tasks, reversal requires keeping Unified CM active and maintaining the Local Gateway interconnect[^22][^66].

**Mixed: some locations on cloud PSTN, others on Local Gateway**

### Do
Access Migrate Unified CM to Webex Calling in Control Hub under Services, Upgrades and Migrations[^101]. In Step 2, click Action, select Import user list, and upload the Unified CM `.tar` file[^20]. Use the standard CSV template fields[^17]. Set a task name of 8 or more characters[^24]. Map device pools to locations and assign Calling Professional or CX Essentials to users and Workspace or Professional Workspace to workspaces[^18][^74][^75]. Stay within the limit of 1000 users and 1000 devices per task[^120]. Pre-load numbers in Control Hub up to 1000 at a time in E.164 format for Local Gateway locations[^63]. Select Prepare to Migrate at the Review screen[^23].

### Verify
Download the Review step reports and verify number allocations location by location against the recorded PSTN architecture[^23].

### Rollback
WarmTransfer's reading of the sources is that no native task reversal exists in Control Hub, requiring retention of the on-premises Unified CM configuration[^22][^66].

## Step 12: Apply the device manifest to Unified CM

### Do
On Unified CM Administration, navigate to Bulk Administration, Upload/Download Files, click Add New, and upload the CSV file with Target set to Phone and Transaction Type set to Update Phone - Custom File[^21]. Navigate to Bulk Administration, Phones, Update Phones, select Custom File, choose the uploaded file, execute the update, and monitor the Job Scheduler[^21].

### Verify
Confirm through Job Scheduler that the update job completes successfully, and verify that phones display an active registration status under Devices in Control Hub[^21][^41].

### Rollback
WarmTransfer's reading of the sources is that there is no supported undo action once devices transition away from Unified CM; backout involves manually updating phone configuration settings back to the Unified CM cluster[^22][^66].

## Step 13: Migrate group telephony features

**No call park or call pickup groups in scope**

### Do
Navigate in Control Hub to Services, Updates and Migrations, Migration utilities, and open Migrate features from Unified CM[^102]. Upload a Unified CM `.tar` export of at most 350 MB, and optionally attach a Unity Connection export from the CallHandlerDataDump tool as a `.zip` up to 2 GB[^118][^122]. Export the resulting CSV files, resolve errors, delete the Errors and Notes columns, and upload the modified CSVs back to Control Hub[^38].

### Verify
Execute acceptance testing covering auto attendant menu trees and greetings, hunt group distribution algorithms, and call queue routing logic[^47].

### Rollback
If CSV files produce import errors, remove the uploaded `.tar` archive using the Delete option and upload again[^37]. Suggested rollback: Delete created call queues, hunt groups, and auto attendants directly within Control Hub calling features.

**Call park and/or call pickup groups are in use and must be rebuilt**

### Do
Access Migrate features from Unified CM in Control Hub under Services, Updates and Migrations, Migration utilities[^102]. Upload the Unified CM `.tar` file (up to 350 MB) and optional Unity Connection export (up to 2 GB)[^118][^122]. Correct flagged CSV errors, delete the Errors and Notes columns, and re-import[^38]. Users linked by shared lines, hunt groups, call queues, call park, and call pickup groups are identified as needing to move in the same batch[^48].

### Verify
Beyond testing call queues, hunt groups, and auto attendants[^47], test call park and call pickup feature operation across migrated endpoints. Suggested check: Test call park and call pickup operations between migrated test extensions.

### Rollback
Delete faulty `.tar` uploads in the features tool and repeat[^37]. Suggested rollback: Remove configured call park extensions and pickup groups from Control Hub feature menus.

## Step 14: Acceptance testing and closeout

**Flash-cut: everything moves in a single migration window**

### Do
Perform the documented acceptance testing suite: user provisioning against directory records, extensions, DID assignments, inbound and outbound PSTN routing with caller ID, on-net calls with hold, transfer, forwarding, and conferencing, queue and hunt group algorithms, auto attendant greetings, and voicemail access[^47]. Once acceptance testing passes, transition to the Optimize phase to decommission on-premises Unified CM infrastructure, optimise PSTN, and monitor service analytics[^65][^96][^97]. Phase 2 is fully cloud with all users on Webex Calling[^97].

### Verify
Suggested check: Verify that active registration counters on the call processing cluster show no remaining endpoints before beginning server decommissioning.

### Rollback
Suggested rollback: Maintain the server cluster in an idle, powered state through a complete billing cycle before permanent hardware decommissioning.

**Phased: groups move over an extended period with both platforms live**

### Do
Execute the complete acceptance test plan across user calling, DID routing, PSTN trunking, feature queues, auto attendants, and voicemail retrieval for each batch[^47]. Operate the deployment in Phase 1 dual call control hybrid coexistence for as long as required; Cisco permits organisations to remain indefinitely in this coexistence state[^97][^105]. Decommission on-premises infrastructure only during the Optimize phase after the final batch moves[^65].

### Verify
Repeat inter-platform test calls and unknown extension routing checks after every migrated batch to confirm routing boundaries remain intact[^54][^93].

### Rollback
WarmTransfer's reading of the sources is that for any failed batch, the safety net is keeping the Unified CM configuration and the Local Gateway interconnect in place so unmigrated and migrated users still reach each other[^66].

## Applicability

Applies to: Cisco Unified Communications Manager, Cisco, Cisco Webex Calling, Cisco Webex Calling Dedicated Instance, Cisco IP Phone 7800 Series, Cisco Webex Contact Center, Cisco IP Phone 8800 Series, and Cisco Webex. Deployments: cloud, on-premises, multi-tenant, dedicated instance, hcs, hybrid-webex-calling-with-onprem-unified-cm, and on-premises-unified-cm. Sources checked 2026-09-16. The end-of-life announcement for Cisco Version 14 on-premises calling applications under perpetual licensing was distributed on 7 October 2024[^7]. The end-of-sale date for Version 14 perpetual on-premises calling applications was 7 April 2025[^129], the last ship date for perpetual SKUs was 6 July 2025[^130], the end of software maintenance releases was 7 April 2026[^6], and the last date of support is 30 April 2027[^8]. The most recent Unified CM release documented at the time of research is Release 15SU4a (build 15.0.1.14901-2) paired with IM and Presence Service Release 15SU4 (build 15.0.1.14900-8)[^131][^132]. Cisco states that Webex Calling data centre locations do not apply to Webex Calling Dedicated Instance[^133][^134], and there are no new Dedicated Instance deployments in the EMEA region[^135].

## What remains uncertain

The migration of stored voicemail message audio bodies from Cisco Unity Connection to Webex Calling is not covered by the sources below. Specific CLI commands and configuration syntax for third-party session border controller vendors providing certificate-based Local Gateway trunks are not covered by the sources below. Reversion procedures for converting Multiplatform firmware back to Enterprise phone firmware are not covered by the sources below.

## Sources

[^1]: Migration Insights also takes a Unified CM BAT .tar as its input, with CDR data uploaded separately as a .gzip. Source: [Migration insights](https://help.webex.com/en-us/article/svoi86/Migration-Insights), Prerequisites; Migration Insights. Checked 2026-09-22.
[^2]: The Control Hub migration upload accepts a Unified CM .tar of at most 350 MB. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Migration of data, upload step. Checked 2026-09-22.
[^3]: Cisco says the BAT .tar can be used to migrate auto attendants, devices, configured lines, device layout (speed dials and shared lines), virtual lines, call queues, hunt groups, call park and user call forwarding and monitoring data. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Migration of data. Checked 2026-09-22.
[^4]: The migration tool's ImportDataBulk.csv output contains data extracted from enduser.csv, phone.csv and device_pool.csv in the imported Unified CM tar. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Export ZIP file, ImportDataBulk.csv entry. Checked 2026-09-22.
[^5]: Cisco's Control Hub Unified CM to Webex Calling migration tells administrators to use the Unified CM Bulk Admin Tool to get the tar files and upload the .tar in Step 2: Import Data. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 2: Import Data. Checked 2026-09-22.
[^6]: The end of software maintenance releases for Version 14 perpetual on-premises calling applications was 7 April 2026, meaning Cisco may no longer issue maintenance or bug-fix builds for that release. Source: [End-of-Sale and End-of-Life Announcement for the Cisco Version 14 of On-premises Calling applications (including Cisco Unified Communications Manager) — Perpetual](https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-communications-manager-callmanager/v-14-premises-calling-applications-eol.html), Milestone table, End of SW Maintenance Releases Date. Checked 2026-09-04.
[^7]: The end-of-life announcement for Cisco Version 14 on-premises calling applications under perpetual licensing, including Unified Communications Manager, was distributed on 7 October 2024. Source: [End-of-Sale and End-of-Life Announcement for the Cisco Version 14 of On-premises Calling applications (including Cisco Unified Communications Manager) — Perpetual](https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-communications-manager-callmanager/v-14-premises-calling-applications-eol.html), Milestone table, End-of-Life Announcement Date. Checked 2026-09-04.
[^8]: The last date of support for Version 14 perpetual on-premises calling applications is 30 April 2027, after which Cisco states all support services are unavailable and the product is obsolete. Source: [End-of-Sale and End-of-Life Announcement for the Cisco Version 14 of On-premises Calling applications (including Cisco Unified Communications Manager) — Perpetual](https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-communications-manager-callmanager/v-14-premises-calling-applications-eol.html), Milestone table, Last Date of Support. Checked 2026-09-04.
[^9]: An estate standardised on Cisco 6800 series phones running Enterprise firmware faces hardware replacement rather than firmware conversion, so a migration business case built only on licence costs will understate the true cost (inferred). Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Prepare, Inventory existing devices and clients, Desk Phones, page 28. Checked 2026-09-16.
[^10]: A migration that concentrates many users into a single Webex Calling location served by 1 registration-based Local Gateway can reach the documented 250 concurrent call ceiling at peak, at which point Cisco states the limit is enforced and additional calls are rejected by the Webex Calling access session border controllers rather than by the carrier (inferred). Source: [Cisco Preferred Architecture for Webex Calling — Design Overview](https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/Collaboration/hybrid/AltDesigns/PA-WbxCall.pdf), Registration-based Local Gateway page 23, Table 2 page 26 and Location Definitions pages 60-61. Checked 2026-09-16.
[^11]: The WebexSamples repository named ucmtowxc-migrationapi, whose name signals a Unified CM to Webex Calling migration API, is archived with a last push of 3 July 2023 and carries no description or licence. Source: [WebexSamples/ucmtowxc-migrationapi](https://github.com/WebexSamples/ucmtowxc-migrationapi), GitHub API archived, pushed_at, description and license fields. Checked 2026-09-04.
[^12]: From Unified CM Release 12.5(1)SU2 onward the Cloud-Connected UC agent code is built into the release, so no agent installer COP file needs to be created and the node connects to Control Hub through a CLI command. Source: [Set up Webex Cloud-Connected UC for on-premises devices](https://help.webex.com/en-us/article/nzt6c0b/Set-up-Webex-Cloud-Connected-UC-for-on-premises-devices), Section: Built-in agent availability. Checked 2026-09-16.
[^13]: Cloud-Connected UC onboarding from the Unified CM admin CLI uses utils ucmgmt organization with the organization id followed by utils ucmgmt agent enable, after which the node is onboarded within a few minutes. Source: [Set up Webex Cloud-Connected UC for on-premises devices](https://help.webex.com/en-us/article/nzt6c0b/Set-up-Webex-Cloud-Connected-UC-for-on-premises-devices), Section: CLI command for onboarding, commands 1 and 2. Checked 2026-09-16.
[^14]: Where the built-in agent is not available, an Agent Cisco Operations Package COP file is created in Control Hub and installed on all nodes of the Unified CM or IM and Presence cluster, and proxy information for internet connectivity is entered when the agent file is created. Source: [Set up Webex Cloud-Connected UC for on-premises devices](https://help.webex.com/en-us/article/nzt6c0b/Set-up-Webex-Cloud-Connected-UC-for-on-premises-devices), Sections: COP file creation and Proxy configuration. Checked 2026-09-16.
[^15]: Cloud-Connected UC is the gate on the automated paths through the migration: without it the CDR-based usage reports in Migration Insights and the in-Control-Hub firmware migration are unavailable and the administrator falls back to BAT file exchange for every device change (inferred). Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Application to Unified CM phones, comparison of auto and manual methods, read with Migration Insights CDR upload. Checked 2026-09-16.
[^16]: Cloud-Connected UC onboarding is verified by matching the verification code shown in the node's installation logs and sign-in pages against the code shown in Control Hub before accepting the node into a cluster group. Source: [Set up Webex Cloud-Connected UC for on-premises devices](https://help.webex.com/en-us/article/nzt6c0b/Set-up-Webex-Cloud-Connected-UC-for-on-premises-devices), Sections: Cluster group assignment and Verification process. Checked 2026-09-16.
[^17]: The migration CSV template carries the fields CUCM USER ID, EMAIL ID, DEVICE MAC, CUSTOM DEVICE POOL and USER AREA CODE. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 2: Import data, CSV template fields. Checked 2026-09-16.
[^18]: Within the migration task, Unified CM device pools are mapped to Webex Calling locations or left as Undefined for later configuration, and warnings about devices mapped to multiple locations must be resolved before proceeding. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 3: Map device pool to locations and Assign location. Checked 2026-09-16.
[^19]: The data migration flow lists an active Webex Calling subscription with entitlement PID A-FLEX-P-CALL as a prerequisite, alongside organisation administrator access to Control Hub. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Section: Prerequisites. Checked 2026-09-16.
[^20]: Data is loaded into the migration flow at Step 2 Import data by choosing Action then Import user list and uploading the Unified CM .tar file, and only on success does the Create a New Task button in Step 3 become enabled. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 2: Import data. Checked 2026-09-16.
[^21]: The post-migration manifest is applied on Unified CM through Bulk Administration Upload/Download Files, adding the CSV with Target set to Phone and Transaction Type set to Update Phone - Custom File, then running Bulk Administration, Phones, Update Phones, Custom File and monitoring the Job Scheduler. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Section: Post-migration steps, steps 2 to 6. Checked 2026-09-16.
[^22]: The Unified CM data migration article documents no rollback or back-out procedure for a completed migration task, so reversal has to be planned as a manual re-registration of devices to Unified CM rather than as a supported product action (inferred). Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Whole article; absence of any rollback or back-out section. Checked 2026-09-16.
[^23]: Selecting Prepare to Migrate at the Review step runs the pre-migration activities, which include creating a profile for each device in the Webex App. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 3: Review. Checked 2026-09-16.
[^24]: A Unified CM data migration task requires a unique task name of at least 8 characters. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 3: Migration task creation, Create task. Checked 2026-09-16.
[^25]: Webex identifies the users being migrated by the Unified CM email ID when numbers are assigned to users and workspaces, and workspaces are toggled manually. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Step 3: Assign numbers to users/workspaces. Checked 2026-09-16.
[^26]: Extension length in Webex Calling is a fixed global setting, so every extension in a Webex Calling deployment has the same length. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Define the dial plan, Webex Calling side. Checked 2026-09-16.
[^27]: Four user provisioning methods are documented: manual assignment in Control Hub, automatic licence templates, bulk CSV upload, and API-based assignment, with automatic templates requiring valid phone numbers to already exist in the location. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Provision users. Checked 2026-09-16.
[^28]: Each Webex Calling location must be documented with extension ranges, DID ranges, PSTN steering digits, site code, main number, voicemail number, licence counts, busy-hour concurrent calls, country, time zone, language, contact details, address and emergency dispatchable location. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Provision the locations. Checked 2026-09-16.
[^29]: The design guidance presents three PSTN connectivity options for Webex Calling: Cisco Calling Plans, Cloud Connected PSTN providers, and on-premises PSTN through a Local Gateway. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: PSTN connectivity options. Checked 2026-09-16.
[^30]: Cisco recommends selecting the Webex Calling instance that gives the lowest signalling round-trip times for the largest number of users in the deployment, and notes that the region is difficult to change afterwards. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Identify the data center. Checked 2026-09-16.
[^31]: Cisco recommends single sign-on for user authentication in the migrated deployment, supporting SAML 2.0, OpenID Connect and Webex identity, with multiple identity providers supported for merged or decentralised organisations. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Understand SSO authentication. Checked 2026-09-16.
[^32]: On the Unified CM side the documented dial plan design uses a single partition for +E.164 directory numbers with core routing based on +E.164 route patterns, and enables +E.164 dialling from Unified CM to Webex Calling alongside extension and abbreviated inter-site dialling. Source: [Design to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/nqojzwt/Design-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Define the dial plan, on-premises side. Checked 2026-09-16.
[^33]: Emergency calling configuration is verified by dialling 933 from each location before live 911 routing is enabled; the IVR confirms the caller's ID and the known address. Source: [Enhanced Emergency Calling for Webex Calling](https://help.webex.com/en-us/article/av6oo3/Enhanced-Emergency-Calling-for-Webex-Calling), Section: Verification, 933 test call. Checked 2026-09-16.
[^34]: Enhanced Emergency Calling is enabled for the organisation in Control Hub by entering a HELD Company ID and Secret Key obtained from RedSky and toggling Enhanced Emergency Calling on, then enabling the service location by location. Source: [Enhanced Emergency Calling for Webex Calling](https://help.webex.com/en-us/article/av6oo3/Enhanced-Emergency-Calling-for-Webex-Calling), Sections: Enable E911 integration in Control Hub for your organization and Enable the E911 service for Webex Calling locations. Checked 2026-09-16.
[^35]: The Webex Calling E911 service is documented as addressing RAY BAUM'S Act Phase 2, effective January 2022, which requires accurate dispatchable addresses for nomadic and non-fixed devices, and Kari's Law, which requires notification when a 911 call is placed. Source: [Enhanced Emergency Calling for Webex Calling](https://help.webex.com/en-us/article/av6oo3/Enhanced-Emergency-Calling-for-Webex-Calling), Section: US laws addressed. Checked 2026-09-16.
[^36]: Automatic location detection for emergency calls depends on network wiremap information loaded into RedSky, including wireless access point MAC addresses, LLDP switch data and IP subnets, mapped to buildings and locations with floor or room level detail. Source: [Enhanced Emergency Calling for Webex Calling](https://help.webex.com/en-us/article/av6oo3/Enhanced-Emergency-Calling-for-Webex-Calling), Section: Dispatchable location requirements. Checked 2026-09-16.
[^37]: If the CSV files produced by the features migration tool contain errors, the uploaded .tar file can be removed with the Delete option and the upload repeated. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Section: Verification / error handling. Checked 2026-09-16.
[^38]: Errors flagged in the exported feature CSVs must be resolved and the Errors and Notes columns removed before the CSVs are uploaded back to Control Hub. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Section: Verification. Checked 2026-09-16.
[^39]: Because a single data migration task caps at 1000 users and 1000 devices, a flash-cut of an estate larger than that is not one task but several tasks run inside one cutover window, which sets a practical floor on how long the window can be (inferred). Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Section: Limits, maximum per task, read against the flash-cut approach. Checked 2026-09-16.
[^40]: With Cloud-Connected UC enabled, phones can be migrated directly from Control Hub by selecting the TFTP server type and Unified CM TFTP load server and choosing Migrate Phones, which processes devices in batches of 200. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Application to Unified CM phones, auto-migration. Checked 2026-09-16.
[^41]: Without Cloud-Connected UC, firmware migration is completed by downloading BAT files from Control Hub, uploading them on Unified CM under Bulk Administration Upload/Download Files with Target Phone and Transaction Type Update Phone - Custom File, then confirming completion back in Control Hub. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Application to Unified CM phones, manual migration steps 1 to 5. Checked 2026-09-16.
[^42]: Because the firmware migration article documents no procedure for reverting a phone from Multiplatform firmware back to Enterprise firmware, converting a phone should be treated as the point of no return for that device within a migration window (inferred). Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Whole article; absence of any revert or downgrade section. Checked 2026-09-16.
[^43]: Before running a device firmware migration task, locations must exist with PSTN assigned for each location, all Unified CM users must be imported into Control Hub, and phone firmware must be at version 14.1 or later. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Prerequisites. Checked 2026-09-16.
[^44]: A single device firmware migration task supports a maximum of 1000 devices. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Eligibility check, device count limit. Checked 2026-09-16.
[^45]: The device firmware migration wizard classifies devices as Eligible, Ineligible, or Unknown eligibility, where Unknown means the tool has inadequate information and the migration may or may not succeed; devices with Unknown eligibility can optionally be included in a task. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Eligibility check, three categories. Checked 2026-09-16.
[^46]: A firmware migration task offers Generate device license and add device, which generates licences and provisions the device, or Generate device license only, which requires the devices to already exist in Webex Calling. Source: [Migrate enterprise phone to Webex Calling phone firmware](https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling), Section: Migration options. Checked 2026-09-16.
[^47]: The documented acceptance testing covers user provisioning against the source directory including extensions and DID assignments, inbound and outbound PSTN with caller ID, on-net calls with transfer, hold, forwarding and conferencing, call queue distribution logic, hunt group hunting algorithm, auto attendant greetings and menu trees, and voicemail retrieval. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Acceptance testing, test categories. Checked 2026-09-16.
[^48]: Users who must move in the same batch are identified by BLF monitoring relationships, membership of hunt pilots or call queues, shared lines, call pickup groups, intercom, and executive and administrative assistant pairings. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Migrate users in batches, dependency list. Checked 2026-09-16.
[^49]: When the integration involves multiple on-premises call control systems reached through different trunks, multiple Webex Calling dial plans are required. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Integration with on-premises call control, multiple systems note. Checked 2026-09-16.
[^50]: The documented implementation sequence runs network readiness, initial setup, Webex Calling service settings, procure PSTN, configure locations, integration with on-premises call control, migrate users in batches, provision devices, configure features, and acceptance testing. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Implement article, top-level section headings in order. Checked 2026-09-16.
[^51]: Before each batch is migrated the documented checks are that all users exist in Control Hub, that all their telephone numbers exist in Control Hub, that the directory holds the correct phone number format, and that licensing and settings templates are configured. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Migrate users in batches, validation steps. Checked 2026-09-16.
[^52]: The PSTN connectivity option is selected and phone numbers ordered before calling locations are configured, because a location is provisioned with its PSTN choice and its main and voicemail pilot numbers. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Sections: Procure PSTN and Configure locations. Checked 2026-09-16.
[^53]: Integrating Webex Calling with on-premises call control requires configuring trunks, route groups, enterprise dial plans and both location and global settings. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Integration with on-premises call control. Checked 2026-09-16.
[^54]: Coexistence routing is enabled per location by turning on unknown extension routing and specifying the maximum unknown extension length in the Call Routing between Webex Calling and premises section. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Integration with on-premises call control. Checked 2026-09-16.
[^55]: A calling location requires a valid street address, and in the United States and Canada that address is validated by the platform and used to send PIDF-LO location information for emergency calls. Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Configure locations, emergency calling note. Checked 2026-09-16.
[^56]: The Migration Insights article routes the administrator to Services then Updates and Migrations, where the Migration Insights card is opened with View. Source: [Migration insights](https://help.webex.com/en-us/article/svoi86/Migration-Insights), Section: Access, navigation instruction. Checked 2026-09-16.
[^57]: The Migration Insights export produces a .zip containing named CSV reports including ImportedDataBulk.csv, DeviceEligibility.csv, HuntGroupCallQueueCallParkCallPickUpGroups.csv, sharedlineGroupmigrationreport.csv, FeatureUsageBasedDeviceEligibilityReport.csv, DidUsageReport.csv and UserWorksapceLastUsage.csv. Source: [Migration insights](https://help.webex.com/en-us/article/svoi86/Migration-Insights), Section: Output reports, CSV file list. Checked 2026-09-16.
[^58]: Migration Insights accepts a Unified CM .tar file of at most 350 MB extracted with the Bulk Administration Tool, and optionally a .gzip file of call detail record data of at most 2 GB for enhanced reporting. Source: [Migration insights](https://help.webex.com/en-us/article/svoi86/Migration-Insights), Section: Upload process, steps 1 and 2. Checked 2026-09-16.
[^59]: Registration-based Local Gateway trunks support up to 250 concurrent calls per trunk and work only with Cisco CUBE using digest authentication, while certificate-based trunks are the option for more than 250 concurrent calls per trunk. Source: [Get started with Local Gateway](https://help.webex.com/en-us/article/t9xctu/Get-started-with-Local-Gateway), Section: Trunk type comparison and concurrent call limits. Checked 2026-09-16.
[^60]: Certificate-based Local Gateway trunking is supported on Cisco CUBE from a minimum of Cisco IOS XE Cupertino 17.9.1a, Cisco Secure Routers, Oracle, AudioCodes Mediant, Ribbon, anynode and Italtel NetMatch-S. Source: [Get started with Local Gateway](https://help.webex.com/en-us/article/t9xctu/Get-started-with-Local-Gateway), Section: Supported platforms. Checked 2026-09-16.
[^61]: A Local Gateway requires CUBE calling licences installed on the gateway, a CA root bundle, SIP digest credentials taken from Control Hub, and an enterprise firewall permitting outbound SIP, RTP over UDP and HTTP to the documented Webex Calling addresses and ports. Source: [Prepare your environment](https://help.webex.com/en-us/article/n4cprps/Prepare-Your-Environment-for-Webex-Calling), Sections: License requirements, Security and certificates, Network and firewall configuration. Checked 2026-09-16.
[^62]: Numbers that will be ported later are added with the Activate Numbers Later option, and an inactive number assigned to a user, workspace or feature stays inactive until it is activated. Source: [Manage phone numbers in Control Hub](https://help.webex.com/en-us/article/wkj3f0/Manage-phone-numbers-in-Control-Hub), Sections: Adding phone numbers and Number states and assignment. Checked 2026-09-16.
[^63]: Numbers are added in Control Hub under Services, PSTN and Routing, Numbers by choosing Manage then Add, up to 1000 numbers at a time, in E.164 format except in the United States where national format is accepted. Source: [Manage phone numbers in Control Hub](https://help.webex.com/en-us/article/wkj3f0/Manage-phone-numbers-in-Control-Hub), Section: Adding phone numbers. Checked 2026-09-16.
[^64]: A phone number assigned to a user, workspace or feature cannot be deleted in Control Hub, and bulk deletion is restricted to unassigned numbers. Source: [Manage phone numbers in Control Hub](https://help.webex.com/en-us/article/wkj3f0/Manage-phone-numbers-in-Control-Hub), Section: Deleting phone numbers. Checked 2026-09-16.
[^65]: The Optimize phase of the documented migration covers optimising PSTN configuration, decommissioning on-premises infrastructure, and monitoring and analysing service performance after cutover. Source: [Migrate from Unified CM to Webex Calling](https://help.webex.com/migrate-unified-cm-to-webex-calling), STEP 5: OPTIMIZE, bulleted article list. Checked 2026-09-16.
[^66]: Since neither the data migration nor the firmware migration documents a reverse action, the practical safety net for a batch is keeping the Unified CM configuration and the Local Gateway interconnect in place so unmigrated and migrated users still reach each other, rather than an undo (inferred). Source: [Implement the migration from Unified CM to Webex Calling](https://help.webex.com/en-us/article/q0pgpb/Implement-the-migration-from-Unified-CM-to-Webex-Calling), Section: Integration with on-premises call control, read against the absence of rollback sections in x974bd and n19c71. Checked 2026-09-16.
[^67]: Cisco organises its Unified CM to Webex Calling migration documentation into five sequential phases named Prepare, Plan, Design, Implement and Optimize, each with its own guide. Source: [Migrate from Unified CM to Webex Calling](https://help.webex.com/migrate-unified-cm-to-webex-calling), Landing hub, phase navigation: STEP 1 PREPARE through STEP 5 OPTIMIZE. Checked 2026-09-16.
[^68]: The documented current-environment assessment in the Prepare phase covers licensing, locations and sites, device inventory and eligibility, users, PSTN connectivity, features and feature usage, Cisco integrations including Unity Connection, call recording, and third-party integrations. Source: [Prepare to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/4yz2zd/Prepare-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Assess your current environment, subsection headings. Checked 2026-09-16.
[^69]: Cisco directs administrators to deploy Cloud-Connected UC early in the transition project, ideally before or during the preparation phase. Source: [Prepare to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/4yz2zd/Prepare-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Set up Cloud-Connected UC. Checked 2026-09-16.
[^70]: Cisco recommends verifying during the Prepare phase which Unified CM registered phones are eligible to upgrade to Multiplatform firmware, so that ineligible phones can be replaced or an alternative plan identified before cutover. Source: [Prepare to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/4yz2zd/Prepare-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Device inventory and eligibility. Checked 2026-09-16.
[^71]: Feature assessment is documented as two complementary inputs: static configuration analysed through Control Hub Migration Insights, and dynamic utilisation data from call detail records, registrations and call activity. Source: [Prepare to migrate from Unified CM to Webex Calling](https://help.webex.com/en-us/article/4yz2zd/Prepare-to-migrate-from-Unified-CM-to-Webex-Calling), Section: Features and feature usage. Checked 2026-09-16.
[^72]: Cisco's agent-facing help article for the product is titled Get started with Webex Calling Customer Assist for Agents and uses the name Customer Assist 4 times with 0 occurrences of CX Essentials, while the Unified CM migration article names the license CX Essentials, so the same entitlement appears under 2 names across 2 current Cisco articles (inferred). Source: [Get started with Webex Calling Customer Assist for Agents](https://help.webex.com/en-us/article/n15c125), page title and body of the Customer Assist agents article, against the User Calling license paragraph of the Unified CM migration article. Checked 2026-09-16.
[^73]: To assign a Webex Calling Standard license during a Unified CM migration, the documented path is to use a user CSV file and then the Migrate features from the Unified CM tool rather than the data migration tool. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), section: Call settings, licensing note. Checked 2026-09-05.
[^74]: Users migrated from Unified CM to Webex Calling with the migration tool can be assigned only Calling Professional or CX Essentials licenses. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), section: Call settings, licensing note. Checked 2026-09-05.
[^75]: Workspaces migrated from Unified CM to Webex using the migration tool can be assigned Workspace or Professional Workspace licenses. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), section: Call settings, licensing note. Checked 2026-09-05.
[^76]: Webex App is the only soft client supported by Webex Calling, whereas Unified CM supports both Webex App and Jabber. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Soft Clients. Checked 2026-09-04.
[^77]: Cloud PSTN, whether Cisco Calling Plan or Cloud Connected PSTN, provides PSTN access only for Webex Calling users; calls originating from premises users cannot reach the cloud PSTN through that path. Source: [Configure trunks, route groups, and dial plans for Webex Calling](https://help.webex.com/article/n0xb944/Configure-Trunks-Route-Groups-and-Dial-Plans-for-Cisco-Webex-Calling), PSTN options. Checked 2026-09-04.
[^78]: Cisco 6800 series IP phones cannot be upgraded from Enterprise firmware to Multiplatform firmware, so a 6800 running Enterprise firmware on Unified CM must be replaced rather than converted. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Inventory existing devices and clients, Desk Phones. Checked 2026-09-04.
[^79]: Cisco 7800 and 8800 series phones must be converted from Enterprise firmware to Multiplatform firmware before they can register to Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Desk Phones. Checked 2026-09-04.
[^80]: Older 8800 series units with hardware version VID 14 or earlier will register with Webex Calling but may show performance issues arising from hardware limitations. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Note, Desk Phones. Checked 2026-09-04.
[^81]: The 8845, 8865 and 8865NR have reached end of sale and Cisco does not recommend migrating them to Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Note, Desk Phones. Checked 2026-09-04.
[^82]: The Cisco 9800 series runs PhoneOS, which supports registration to both Unified CM and Webex Calling, so 9800 phones transition without a firmware conversion. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Desk Phones. Checked 2026-09-04.
[^83]: The same guide separately lists the 8845, 8865 and 8875 as personal video phones that are supported with Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Note, Video Endpoints. Checked 2026-09-04.
[^84]: The 8845 and 8865 personal video phones are end-of-sale and not recommended for migration, even though they remain supported with Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Note, Video Endpoints. Checked 2026-09-04.
[^85]: Only the Cisco 6800, 7800, 8800 and 9800 desk phone series are supported with Webex Calling, which is a subset of the phones supported on Unified CM. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Inventory existing devices and clients, Desk Phones. Checked 2026-09-04.
[^86]: Cisco positions Dedicated Instance as a low-disruption migration path from on-premises Unified CM, preserving the same features, user experience and integration options and requiring no retraining for existing Unified CM customers. Source: [Introduction to Dedicated Instance](https://help.webex.com/en-us/article/dk3o5r/Introduction-to-Dedicated-Instance), Simple migration path, No Disruptions. Checked 2026-09-04.
[^87]: On the evidence the corpus holds, the choice between Dedicated Instance and Webex Calling multi-tenant turns on whether an organisation wants to keep its existing Unified CM feature set and administration model or to re-platform onto Webex Calling's native feature set, and Cisco publishes no explicit decision tree and no named migration tool that distinguishes the 2 paths (inferred). Source: [Introduction to Dedicated Instance](https://help.webex.com/en-us/article/dk3o5r/Introduction-to-Dedicated-Instance), synthesis across the three Dedicated Instance articles. Checked 2026-09-16.
[^88]: Migration licences are required for the Enterprise to Multiplatform conversion and are generated through a Cisco web portal; alternatively the firmware and licences can be hosted on Unified CM itself. Source: [Cisco Cloud Upgrader (Enterprise to MPP firmware migration for Webex Calling)](https://upgrade.cisco.com/e2m_converter_wxc), Migration licenses. Checked 2026-09-04.
[^89]: Migration licences are required for the Enterprise to Multiplatform conversion and are generated through a Cisco web portal; alternatively the firmware and licences can be hosted on Unified CM itself. Source: [Cisco Cloud Upgrader (Enterprise to MPP firmware migration for Webex Calling)](https://upgrade.cisco.com/e2m_converter_wxc), Migration licenses. Checked 2026-09-04.
[^90]: The Cisco Cloud Upgrader converts phones running Enterprise firmware on Unified CM or HCS to Multiplatform firmware and applies the licences that enable the calling service after conversion. Source: [Cisco Cloud Upgrader (Enterprise to MPP firmware migration for Webex Calling)](https://upgrade.cisco.com/e2m_converter_wxc), Step 1, Hardware and Licenses. Checked 2026-09-04.
[^91]: The Cisco Cloud Upgrader converts phones running Enterprise firmware on Unified CM or HCS to Multiplatform firmware and applies the licences that enable the calling service after conversion. Source: [Cisco Cloud Upgrader (Enterprise to MPP firmware migration for Webex Calling)](https://upgrade.cisco.com/e2m_converter_wxc), Step 1, Hardware and Licenses. Checked 2026-09-04.
[^92]: A per-location setting for calls to on-premises extensions lets users keep abbreviated dialling, for example 4 digits, while a site is only partially migrated, by routing unmatched extensions of a configured length between 2 and 10 digits to a chosen route group or trunk. Source: [Configure trunks, route groups, and dial plans for Webex Calling](https://help.webex.com/article/n0xb944/Configure-Trunks-Route-Groups-and-Dial-Plans-for-Cisco-Webex-Calling), Configure calls to on-premises extensions. Checked 2026-09-04.
[^93]: A Webex Calling dial plan differentiates destinations bound for the on-premises Unified CM, which are sent as enterprise calls, from all other destinations, which are sent as PSTN calls, over the same trunk or route group. Source: [Cisco Preferred Architecture for Webex Calling — Design Overview](https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/Collaboration/hybrid/AltDesigns/PA-WbxCall.pdf), Interconnect with On-Premises Call Control, page 31. Checked 2026-09-04.
[^94]: During coexistence a Local Gateway can simultaneously provide PSTN access and an interconnect to the existing on-premises call control, and the on-premises call control may remain in permanent use alongside Webex Calling. Source: [Cisco Preferred Architecture for Webex Calling — Design Overview](https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/Collaboration/hybrid/AltDesigns/PA-WbxCall.pdf), Interconnect with On-Premises Call Control, page 31. Checked 2026-09-04.
[^95]: In Cisco's documented coexistence configuration the Local Gateway separates traffic by port: calls arriving from Unified CM on port 5060 are routed to the PSTN and calls arriving on port 5065 are routed to Webex Calling, which requires setting the Unified CM SIP trunk security profile incoming port to 5065. Source: [Configure Local Gateway on Cisco IOS XE for Webex Calling](https://help.webex.com/en-us/article/jr1i3r/Configure-Local-Gateway-on-Cisco-IOS-XE-for-Webex-Calling), Unified CM interconnect dial-peer configuration. Checked 2026-09-04.
[^96]: Cisco defines 2 migration approaches: a flash-cut in which all users and devices move in 1 window after which the on-premises estate can be decommissioned, and a phased approach in which groups move over an extended period. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Migration Approach. Checked 2026-09-04.
[^97]: The phased architecture is described as Phase 0 with Unified CM only on premises, Phase 1 as a hybrid coexistence state with dual call control split between Unified CM and Webex Calling, and Phase 2 as fully cloud with all users on Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Figure 7, Phased Calling Transition: Hybrid and Cloud. Checked 2026-09-04.
[^98]: Cisco states that the supplementary migration utility script creates CallPark.csv and CallPickupgroup.csv files for Webex Calling which the Migrate features from Unified CM tool does not currently support, while that tool does produce a CallParkExtensionBulk.csv containing provisioning data to configure call park extensions. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Migration utility script, script capability list, against the CSV file list entry for CallParkExtensionBulk.csv. Checked 2026-09-16.
[^99]: 2 current Cisco help articles disagree on the Control Hub menu label for the migration area: the Unified CM data migration article says Services then Upgrades and Migrations, while the devices and features article says Services then Updates and Migrations (disputed). Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Access path, step 1-2, compared against x974bd's Login to Control Hub step. Checked 2026-09-04.
[^100]: Control Hub includes a device eligibility tool named Migrate Your Phone to Webex Calling, and selecting the Generate device license only option performs an eligibility check without adding the devices. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Verify device eligibility, Figure 10. Checked 2026-09-04.
[^101]: The Unified CM data migration flow is started in Control Hub under Services, Upgrades and Migrations, on the tile named Migrate Unified CM to Webex Calling. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Login to Control Hub procedure step. Checked 2026-09-04.
[^102]: The devices and features migration tool is reached in Control Hub under Services, Updates and Migrations, in the Migration utilities section, on the Migrate features from Unified CM card. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Access path, step 1-2. Checked 2026-09-04.
[^103]: The devices and features migration tool covers Auto-Attendant, Devices, Configured Lines, Device Layout including speed dial and shared line, Virtual Line, Call Queue, Hunt Group, Call Park, and user calling data comprising call forwarding and call monitoring. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Migration of data, opening sentence. Checked 2026-09-16.
[^104]: Cisco states that 2 reports in the migration export zip, SharedlineGroupMigrationReport.csv and HuntGroup_CallQueue_CallPark_CallPickUpGroups.csv, should be used to identify which users are in relationship with each other for group features and should migrate together. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Export ZIP file section, the sentence naming the 2 group-feature reports. Checked 2026-09-16.
[^105]: Cisco explicitly allows for organisations remaining indefinitely in the Phase 1 dual call control coexistence state with no plan to complete the transition to cloud calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Note under Figure 7. Checked 2026-09-04.
[^106]: Cisco states that when users migrate from Unified CM to Webex Calling using the migration tool they can only be assigned Calling Professional or CX Essentials licenses, that an administrator needing to assign a Webex Standard license must not use that tool and should instead use a user CSV file followed by the Migrate features from Unified CM tool, and that a migrating workspace can be assigned Workspace or Professional Workspace licenses. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Calling license options, User Calling license and Workspace Calling License paragraphs. Checked 2026-09-16.
[^107]: Clicking Complete migration downloads a manifest file in .zip format containing the MAC addresses of phones in a .csv file, which the administrator uploads on Unified CM through Bulk Administration Upload slash Download Files with the target set to Phone and the transaction type set to Update Phone - Custom File in order to start the migration. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Complete migration step 5 and the Bulk Administration upload procedure. Checked 2026-09-16.
[^108]: Migration Insights, reached in Control Hub under Services, Upgrades and Migrations, is offered as the assessment step for deciding whether to migrate to Webex Calling. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Assessment section. Checked 2026-09-04.
[^109]: Cisco's named native migration utilities for this transition are Migration Insights, devices and features migration from Unified CM, a user and contact synchronisation utility, Unified CM data conversion, Enterprise-to-MPP phone firmware conversion, and Jabber to Webex App migration. Source: [Migrate from Unified CM to Webex Calling](https://help.webex.com/migrate-unified-cm-to-webex-calling), Named migration tools. Checked 2026-09-04.
[^110]: The migration flow offers 3 documented number-assignment scenarios by the PSTN model of the Webex locations involved: where all locations are local gateway, Add numbers to location is enabled and Auto assign numbers is greyed out; where all locations are Cloud Connected PSTN or Cisco PSTN, Auto assign numbers is enabled and Add numbers to location is greyed out; and where the locations are a mix of premises-based PSTN and Cloud Connected or Cisco PSTN, both options are greyed out. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Scenarios for Auto Assign numbers and Add numbers to location, Scenario 1 to Scenario 3. Checked 2026-09-16.
[^111]: Phones on Unified CM that are being migrated must be running Phone Load version 14.1 or later. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Before you begin / prerequisites. Checked 2026-09-04.
[^112]: All Unified CM end users must already be provisioned as Webex users, through Cisco Directory Connector or another mechanism, before the migration task runs. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Before you begin / prerequisites. Checked 2026-09-04.
[^113]: Cisco lists business reasons to keep call control on premises: phone models unsupported by Webex Calling, numerous or complex integrations without cloud equivalents, complex dial plans or granular classes of service, unreliable internet access, strict data privacy or ownership rules, on-premises or in-country call recording mandates, third-party integrations without a Webex Calling alternative, and contact-centre integrations not yet moving to cloud. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Figure 2 discussion. Checked 2026-09-04.
[^114]: Cisco recommends moving users onto Webex App while they are still registered to Unified CM calling, and only then cutting them over to Webex Calling. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Soft Clients. Checked 2026-09-04.
[^115]: Cannot be migrated as there is no equivalent feature in WxC is one of 6 documented error and note values for the Auto-AttendantBulk.csv migration report, alongside a location that cannot be derived from the auto attendant number from UNITY, an empty extension column in the source data, a business schedule that does not exist in the location or organisation, a name that cannot be null, and a greetings file that cannot be found in Webex Calling. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Auto-AttendantBulk.csv column table, the errors and notes value list, read as cells. Checked 2026-09-16.
[^116]: Cisco states that the devices and features migration steps also apply to Dedicated Instance, not only to Webex Calling multi-tenant. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), note preceding the Migration of data section. Checked 2026-09-16.
[^117]: Cisco documents a python script named UserBasedUCMFeatureMigration that processes call detail record data collected on a server or Unified CM, filters the output of the Migrate features from Unified CM tool by a user list with an optional Location column override, identifies users who are part of group features but are not in that list, identifies directory numbers existing in multiple device pools and lists them in DNInMultipleDevicePool.csv in the insightDir folder, and creates CallPark.csv and CallPickupgroup.csv. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Migration utility script, the Here is what the script does list. Checked 2026-09-16.
[^118]: The Unified CM .tar file uploaded to the devices and features migration tool is limited to 350 MB. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Import data, file upload step. Checked 2026-09-04.
[^119]: The target architecture adds Webex Calling as the cloud call service, Cisco Directory Connector or the Entra ID wizard application for identity synchronisation, a Local Gateway for PSTN access and Unified CM interoperation, and a Survivability Gateway for fallback calling during outages; Cisco Calling Plan and Cloud Connect require no on-premises equipment. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Core components, Table 3. Checked 2026-09-04.
[^120]: A single Unified CM to Webex Calling migration task can migrate at most 1000 users and 1000 devices; larger estates require multiple migration tasks. Source: [Migrate Unified CM data to Webex Calling](https://help.webex.com/en-us/article/x974bd/Migrate-Unified-CM-to-Webex), Create a migration task, task-name step. Checked 2026-09-04.
[^121]: The recommended project lifecycle has 3 phases distinct from the architecture phases: Pre-Migration covering organisation setup, licensing, user provisioning, network readiness and software upgrades; Migration Prep covering feature definition, Unified CM data extraction, client and phone version planning, testing and pilot; and Migration Rollout and Decommission covering adoption, user and device migration, feature migration and decommissioning the on-premises estate. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Figure 8, Recommended 3-Phase Transition. Checked 2026-09-04.
[^122]: An optional Cisco Unity Connection export produced by the CallHandlerDataDump tool may be uploaded as a .zip file up to 2 GB. Source: [Migrate devices and features from Unified CM to Webex Calling](https://help.webex.com/en-us/article/d2lemv/Migration-of-Devices-and-Features-From-Cisco-unified-Communications-Manager(UCM)-to-Webex-Calling-Multi-Tenant), Import data, Unity upload step. Checked 2026-09-04.
[^123]: Phones returning Unknown from the eligibility check are resolved either by reading the product ID and version ID from the physical phone label, or by running a third-party IP Phone Readiness Tool against Unified CM. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Verify device eligibility. Checked 2026-09-04.
[^124]: Cisco's recommended network targets for good voice quality over the internet are 1-way latency below 100 milliseconds, jitter below 10 milliseconds, and packet loss of 0.5 percent or less. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Network readiness, Latency, Jitter, and Packet Loss Targets. Checked 2026-09-04.
[^125]: Cisco states that the IP Phone Readiness Tool it points to is not an official Cisco tool and is not supported by Cisco TAC, carrying best-effort support only while being free to use. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Verify device eligibility. Checked 2026-09-04.
[^126]: Cisco recommends migrating the contact centre workload alone and treating telephony and public network migration as a separate effort either before or after, to avoid additional complexity and risk. Source: [Contact Center: Transitioning from Cisco Unified Contact Center Enterprise to Webex Contact Center Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CONTACT_CENTER_UnifiedCCE_to_WebexCC.pdf), page 64, PSTN section under Design. Checked 2026-09-05.
[^127]: Cisco states that the initial Webex Calling region selection cannot be changed later, that the decision should be taken early in a transition to avoid excessive signalling round-trip delay, and recommends selecting the Webex Calling instance that provides the lowest signalling round-trip times for the largest number of users in the deployment. Source: [Cisco Preferred Architecture for Webex Calling — Design Overview](https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/Collaboration/hybrid/AltDesigns/PA-WbxCall.pdf), Architectural Overview, Webex Calling Data Centers. Checked 2026-09-16.
[^128]: Converting a Cisco IP Phone to Multiplatform firmware for Webex Calling has hardware version floors: the 7821 and 7861 require hardware version V03 or later and the 7841 requires V04 or later, and the device must run software version 11.3.1MES5 or later. Source: [Supported devices for Webex Calling](https://help.webex.com/en-us/article/qkwt4j/Supported-Devices-for-Webex-Calling), List of supported Cisco devices, IP Phones row. Checked 2026-09-16.
[^129]: The end-of-sale date for Version 14 perpetual on-premises calling applications was 7 April 2025. Source: [End-of-Sale and End-of-Life Announcement for the Cisco Version 14 of On-premises Calling applications (including Cisco Unified Communications Manager) — Perpetual](https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-communications-manager-callmanager/v-14-premises-calling-applications-eol.html), Milestone table, End-of-Sale Date. Checked 2026-09-04.
[^130]: The last ship date for Version 14 perpetual on-premises calling application SKUs was 6 July 2025. Source: [End-of-Sale and End-of-Life Announcement for the Cisco Version 14 of On-premises Calling applications (including Cisco Unified Communications Manager) — Perpetual](https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-communications-manager-callmanager/v-14-premises-calling-applications-eol.html), Milestone table, Last Ship Date. Checked 2026-09-04.
[^131]: Build numbers for that release are 15.0.1.14901-2 for Unified Communications Manager 15SU4a and 15.0.1.14900-8 for IM and Presence Service 15SU4. Source: [Release Notes for Cisco Unified Communications Manager Release 15SU4a and the IM and Presence Service Release 15SU4](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/rel_notes/15/SU4/cucm_b_release-notes-for-cucm-imp-15su4.html), Version numbers line. Checked 2026-09-04.
[^132]: The most recent Cisco Unified Communications Manager release documented at the time of research is Release 15SU4a, paired with IM and Presence Service Release 15SU4. Source: [Release Notes for Cisco Unified Communications Manager Release 15SU4a and the IM and Presence Service Release 15SU4](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/rel_notes/15/SU4/cucm_b_release-notes-for-cucm-imp-15su4.html), Document title. Checked 2026-09-04.
[^133]: Cisco states that the Webex Calling data centre location information does not apply to Webex Calling Dedicated Instance. Source: [Data Center locations for Webex Calling](https://help.webex.com/en-us/article/n70gvam/Data-Center-locations-for-Webex-Calling), closing note after Table 2. Checked 2026-09-16.
[^134]: The Webex Calling data centre location article explicitly excludes Webex Calling Dedicated Instance from its scope. Source: [Data Center locations for Webex Calling](https://help.webex.com/en-us/article/n70gvam/Data-Center-locations-for-Webex-Calling), closing note. Checked 2026-09-05.
[^135]: Cisco states there are no new Dedicated Instance deployments in the EMEA region, so new customers in that region must choose a different data centre region. Source: [Activate Dedicated Instance](https://help.webex.com/en-us/article/nefkee9/How-to-Activate-Dedicated-Instance), Region selection guidance. Checked 2026-09-04.