Unified CM and Webex Calling coexistence during a migration
Verified 2026-09-24 · 60 sources · tier 2
Also known as coexistence dual call control.
Cisco describes the coexistence phase of a Unified CM to Webex Calling migration as one in which some users, devices, and soft clients have moved to Webex Calling while others remain on on-premises Unified CM call control 28. Cisco names two migration approaches—flash-cut (where all users and devices move at the same time) and phased—and notes that most organizations select the phased approach 30.
Coexistence model and timeline
Cisco states that an organization may remain in the coexistence dual call control phase for an extended period of months or even years 29. Cisco also states that some organizations keep a coexistence dual call control deployment indefinitely, with no plan to move fully to cloud calling 13.
PID A-FLEX-P-CALL provides temporary licensing for up to 18 months during the transition, with basic-level support on both calling environments 8.
Interconnection and Local Gateway requirements
During coexistence, calls between on-premises Unified CM users and Webex Calling users traverse the Local Gateway connection 15. For dual call control, Cisco specifies deploying 1 or more Local Gateways for on-premises PSTN to enable calling between Webex Calling and Unified CM endpoints 12. Cisco states that the connection between on-premises and Webex Calling must be designed and sized for the expected number of concurrent calls and required redundancy 18.
A single registration-based Local Gateway supports up to 250 concurrent calls, whereas certificate-based connectivity supports more—up to 6500 depending on SBC model and connectivity type 17. Cisco states that one-way latency between the Local Gateway and the Webex Calling access SBC should not exceed 100 ms 16.
Cisco instructs administrators to create a trunk and a route group for each Local Gateway and assign the route group as the location's PSTN choice; Cisco recommends always choosing a route group so trunks can be added later for scale and redundancy 19.
Dial plan configuration
During the transition, the Unified CM dial plan must support +E.164 dialing and extension dialing to Webex Calling, both intra-site and inter-site when extension ranges are unique 52. The Unified CM transition dial plan must also support abbreviated inter-site dialing, forced on-net dialing from Unified CM to Webex Calling, and call-back from the missed calls directory to destinations on Webex Calling 5021. In the reverse direction, the transition dial plan must support forced on-net dialing and inter-site extension dialing from Webex Calling to Unified CM 60.
The transition dial plan must also carry PSTN calls from Webex Calling via on-premises PSTN when used, and PSTN calls from Unified CM via Webex Calling when PSTN trunking for hybrid deployments is used 38.
Unified CM routing logic
Cisco's coexistence design adds a Webex Calling partition to the Unified CM dial plan containing +E.164 route patterns for all Webex Calling destinations 59. To avoid call loops, the inbound calling search space (CSS) on the Unified CM trunk from the Local Gateway should not have access to the Webex Calling partition 14.
Under Unified CM best-match routing, a +E.164 directory number still provisioned on Unified CM wins over a wildcarded +E.164 route pattern pointing to Webex Calling, ensuring calls to that number remain on Unified CM 1. Cisco's example calling search space for calls arriving from Webex includes partitions for +E.164 directory numbers (DN), abbreviated inter-site dialing (ESN), and PSTN access (PSTNInternational) 51. Unified CM configuration adds abbreviated inter-site dialing normalization for Webex destinations, translating enterprise numbers to +E.164 before routing to the Webex partition 53.
Webex Calling routing and dial plan rules
When on-premises call control is integrated, Webex Calling enterprise dial plans should contain only the patterns needed to route calls to on-premises destinations 58. Webex Calling dial plans are configured globally for the enterprise, apply to all users regardless of location, and route matching calls to on-premises destinations over a trunk or route group 57. Webex Calling dial plan patterns may be +E.164 patterns, enterprise dial patterns without a leading plus, or SIP URI domain patterns; wildcards X and ! are supported but cannot be combined in one pattern 4.
Internal extension length in Webex Calling can be set from 2 to 10 digits, with a default of 4 7. The Webex Calling 'Calls to On-Premises Extensions' setting is enabled per location and routes calls from that location's users to unknown extensions of 2 to 10 digits to a selected route group or trunk as premises calls 26. For unknown-extension handling, Standard Behavior is the default and recommended option for PBX interoperability; Legacy Behavior exists for backward compatibility and is not recommended when dial plans are configured 46.
Webex Calling's 'Allow extension dialing between locations' toggle should be enabled only when the organization has no duplicate extensions across its locations 6. If extension ranges overlap across sites, Cisco states an enterprise numbering plan must be created by prefixing extensions with an access code and a site code 27. In Cisco's migration design:
- All site codes of all locations must be unique and have the same length 44.
- Each location's routing prefix must be unique, with a routing prefix length of 1 to 7 digits 43.
- No extension range may start with the inter-site steering digit or the PSTN steering digit 47.
PSTN connectivity and number porting
A Control Hub location can be assigned only 1 PSTN option: Cisco Calling Plans, Cloud Connect, or on-premises PSTN via Local Gateway 25. PSTN trunking for hybrid Webex Calling deployments allows on-premises PBXs such as Unified CM to place and receive PSTN calls through Webex Calling using Cloud Connected Partner PSTN or Local Gateway PSTN 11.
Cisco describes retaining on-premises PSTN throughout the transition—migrating PSTN per location as users move—as one option; Webex Calling users then use on-premises PSTN via the Local Gateway connection 39. Cisco notes that moving PSTN to a Cloud Connected PSTN provider at the start while keeping Unified CM during a phased migration adds complexity and risk, particularly in adapting existing Unified CM call routing 2.
Number porting can be executed as a single coordinated cutover once the Webex Calling migration is complete, or incrementally per location as users move 35. Porting challenges listed by Cisco include coordinating port orders precisely, potential delays, and provider limits such as caps on concurrent port requests 34. For Cisco Calling Plan ports, customers can change or cancel a port order in Control Hub before the losing carrier provides FOC; after FOC, changes require a support case with Cisco PSTN Technical Services 33.
In Control Hub, numbers can be moved between locations only within the same country and from the same PSTN provider or Local Gateway; a location's main number cannot be moved 24.
User transition and service integration
Cisco recommends moving users together when they depend on each other through BLF monitoring, the same hunt pilot or group, shared lines, the same pickup group, shared call-park numbers, intercom, or admin/exec relationships 22. Cisco's implementation checklist directs administrators to disable or delete the user and device directory number and calling features on Unified CM after the user transitions to Webex Calling 40. Users migrated to Webex Calling can search the Webex directory for enterprise users still on Jabber or Unified CM 5.
Cisco's Hybrid Messaging Service connects the on-premises Unified CM IM and Presence Service to Webex so users still on Jabber and users moved to Webex App can communicate 9. Webex Calling Customer Assist can be deployed for agents while other employees stay on Unified CM, interconnected through Local Gateway; this requires Unified CM clusters on version 14 or 15 with SUs or later 3.
Webex Calling cannot integrate with premises-based voicemail systems such as Unity Connection or Unity Connection Express 55. Furthermore, there is no native way to migrate existing Unity Connection voicemail messages or greetings to Webex Calling voicemail 23.
The Control Hub Unified CM migration tool migrates at most 1000 users and 1000 devices per task, requiring multiple tasks for larger migrations 48. The export/import migration covers auto attendants, devices, configured lines, device layout including shared lines, virtual lines, call queues, hunt groups, call park, and user call forwarding and monitoring 49. Phones on Unified CM that are being migrated must run phone load version 14.1 or later 31.
See also
- See also CUCM to Webex Calling migration.
- See also Building a hybrid Unified CM and Webex Calling environment for a phased migration.
- See also Setting up a Webex Calling Local Gateway.
- See also CUBE dial-peer matching and voice class URI and translation profiles.
- See also Jabber to Webex App migration.
- See also Unified CM translation and transformation patterns.
- See also Unified CM hunt pilots and hunt lists and line groups.
- See also Unified CM call pickup and call park.
Applicability
Phones migrating from Unified CM must run phone load version 14.1 or later 31. Unified CM clusters deploying Webex Calling Customer Assist must be on version 14 or 15 with SUs or later 3. Modifying Cisco Calling Plan port orders directly in Control Hub applies only to Cisco Calling Plan ports 33.
What remains uncertain
Emergency calling and ELIN or location handling for users split across Unified CM and Webex Calling is not covered by the sources below. Cross-platform forward-to-voicemail and MWI when caller and callee are on different platforms is not covered by the sources below. Whether shared lines / hunt groups / pickup / BLF can span Unified CM and Webex Calling is not covered by the sources below. Dedicated Instance as a coexistence or migration alternative is not covered by the sources below. Inbound PSTN to Unified CM through hybrid PSTN trunking and the capacity per route list figure is not covered by the sources below. Presence for Unified CM users on Webex App (Calling in Webex App Unified CM) versus Jabber with IM and Presence during coexistence is not covered by the sources below. Certificate-based Local Gateway concurrent call capacity by platform model is not covered by the sources below. Porting procedures for Cloud Connect providers and Local Gateway carriers (non Cisco Calling Plan) are not covered by the sources below.
See also
Referenced by
- Analysing a SIP call in Wireshark — CUBE hairpin and ITSP media signatures apply to hybrid trunks
- Building a hybrid Unified CM and Webex Calling environment for a phased migration — Sibling topic packet on coexistence was being researched in the same run; not read here and no claims reused.
- CUBE dial-peer matching and voice class URI and translation profiles — Webex Calling Local Gateway on IOS XE uses voice class uri pattern dtg= plus incoming uri request and voice class dpg
- Setting up a Webex Calling Local Gateway — The ucm=behind branch is the gateway half of Unified CM and Webex Calling coexistence
- Troubleshooting Cisco IP phone registration — Phones moved between Unified CM clusters or platforms hit the ITL signer mismatch covered in step 6.
- Unified CM Extension Mobility and cross-cluster Extension Mobility — Webex Calling Hoteling and hot desking are the cloud counterparts for hoteling-style use; the migration mapping is unresearched
- Unified CM Session Management Edition — Webex Calling Dedicated Instance offers SME for multi-cluster and multi-region customers
- Unified CM backup and upgrade — Clusters that stay on-premises during a hybrid migration still need to be on a supported Unified CM release; this packet covers the upgrade mechanics only
- Unified CM call pickup and call park — Pickup groups and park ranges must be re-expressed when users move from Unified CM to Webex Calling. Proposed by this packet; mapping itself is unresearched (see frontier).
- Unified CM hunt pilots and hunt lists and line groups — Hunt pilot / hunt list / line group chains must be mapped to Webex Calling hunt groups or call queues during migration; mapping not researched here (see frontier)
- Unified CM translation and transformation patterns — A +E.164 globalized dial plan is the basis for routing between Unified CM and cloud calling; not researched in this packet
- Webex Calling device onboarding and activation codes — Enterprise-to-MPP firmware migration of UCM phones (migration license via activation code field; Control Hub migration wizard) is the device leg of UCM to Webex Calling moves
- Unified CM and Teams Phone coexistence during a migration — The same wave-migration problem; with Webex Calling as the target instead of Teams Phone
Sources
- 1Unified CM best-match routing means a +E.164 directory number still provisioned on Unified CM wins over a wildcarded +E.164 route pattern pointing to Webex Calling, so calls to that number stay on Unified CM.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (best match paragraph) · Checked 2026-09-24
- 2Cisco says moving PSTN to a Cloud Connected PSTN provider at the start while keeping Unified CM during a phased migration adds complexity and risk, particularly in adapting existing Unified CM call routing.Design to migrate from Unified CM to Webex Calling · Design to migrate > PSTN · Checked 2026-09-24
- 3Webex Calling Customer Assist can be deployed for agents while other employees stay on Unified CM, interconnected through Local Gateway; Unified CM clusters must be version 14 or 15 with SUs or later.Configure Webex Calling Customer Assist for Unified Communications Manager · Configure Webex Calling Customer Assist for Unified Communications Manager > Customer Assist; requirements · Checked 2026-09-24
- 4Webex Calling dial plan patterns may be +E.164 patterns, enterprise dial patterns without a leading plus, or SIP URI domain patterns; wildcards X and ! are supported but cannot be combined in one pattern.Configure trunks, route groups, and dial plans for Webex Calling · Configure trunks, route groups, and dial plans > Dial plans > dial patterns · Checked 2026-09-24
- 5Cisco says users moved to Webex Calling can search the Webex directory for enterprise users still on Jabber or Unified CM.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > Users · Checked 2026-09-24
- 6Webex Calling's 'Allow extension dialing between locations' toggle should be enabled only when the organization has no duplicate extensions across its locations.Configure your Webex Calling dial plan · Configure your Webex Calling dial plan > Internal dialing · Checked 2026-09-24
- 7Webex Calling internal extension length can be set from 2 to 10 digits, with a default of 4.Configure your Webex Calling dial plan · Configure your Webex Calling dial plan > Internal Extension Length · Checked 2026-09-24
- 8PID A-FLEX-P-CALL provides temporary licensing for up to 18 months during the transition, with basic-level support on both calling environments.Migrate Unified CM data to Webex Calling · Migrate Unified CM data to Webex Calling > Before you begin · Checked 2026-09-24
- 9Cisco's Hybrid Messaging Service connects the on-premises Unified CM IM and Presence Service to Webex so users still on Jabber and users moved to Webex App can communicate.Upgrade Jabber with IM and Presence to Webex App · Upgrade Jabber with IM and Presence to Webex App > Hybrid Messaging Service · Checked 2026-09-24
- 10Per the 2018 Hybrid Message guide, group spaces and group chats are not converted between Webex App and Jabber, and Jabber users cannot send files to Webex App users.Deployment Guide for Hybrid Message - Cisco Webex Hybrid Message Service Overview · Hybrid Message Service Overview > Group messaging; File transfer · Checked 2026-09-24
- 11PSTN trunking for hybrid Webex Calling deployments lets on-premises PBXs such as Unified CM place and receive PSTN calls through Webex Calling using Cloud Connected Partner PSTN or Local Gateway PSTN.PSTN trunking for hybrid Webex Calling deployments · PSTN trunking for hybrid Webex Calling deployments > overview · Checked 2026-09-24
- 12For dual call control, Cisco says to deploy one or more Local Gateways for on-premises PSTN to allow calling between Webex Calling and Unified CM endpoints.Implement the migration from Unified CM to Webex Calling · Implement the migration > Integration with on-premises call control · Checked 2026-09-24
- 13Cisco states some organizations may keep a coexistence dual call control deployment indefinitely with no plan to fully move to cloud calling.Introduction (Migrate Unified CM to Webex Calling) · Introduction > Migration approach · Checked 2026-09-24
- 14To avoid call loops, the inbound calling search space on the Unified CM trunk from the Local Gateway must not have access to the Webex Calling partition.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM · Checked 2026-09-24
- 15During coexistence, calls between on-premises Unified CM users and Webex Calling users traverse the Local Gateway connection.Design to migrate from Unified CM to Webex Calling · Design to migrate from Unified CM to Webex Calling > PSTN · Checked 2026-09-24
- 16Cisco says one-way latency between the Local Gateway and the Webex Calling access SBC should not exceed 100 ms.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > PSTN connectivity · Checked 2026-09-24
- 17Cisco states a single registration-based Local Gateway supports up to 250 concurrent calls, and certificate-based connectivity can support more, up to 6500 depending on connectivity type and SBC model.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > PSTN connectivity · Checked 2026-09-24
- 18Cisco says the connection between on-premises and Webex Calling must be designed and sized for the expected number of concurrent calls and the required redundancy.Design to migrate from Unified CM to Webex Calling · Design to migrate from Unified CM to Webex Calling > PSTN · Checked 2026-09-24
- 19Cisco says to create a trunk and a route group for each Local Gateway and assign the route group as the location's PSTN choice, and recommends always choosing a route group so trunks can be added later for scale and redundancy.Implement the migration from Unified CM to Webex Calling · Implement the migration > Integration with on-premises call control · Checked 2026-09-24
- 20When creating a Webex Calling location, two DIDs must be provisioned: one as the location main number and one for the voicemail portal.Design to migrate from Unified CM to Webex Calling · Design to migrate > Locations · Checked 2026-09-24
- 21The Unified CM transition dial plan must support call-back from the missed calls directory to destinations on Webex Calling.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (bulleted list of transition requirements) · Checked 2026-09-24
- 22Cisco recommends moving users together when they depend on each other through BLF monitoring, the same hunt pilot or group, shared lines, the same pickup group, shared call-park numbers, intercom or admin/exec relationships.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > Users · Checked 2026-09-24
- 23There is no native way to migrate existing Unity Connection voicemail messages or greetings to Webex Calling voicemail.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > Cisco integrations: Unity Connection UCCX UCCE · Checked 2026-09-24
- 24Control Hub can move numbers between locations only within the same country and from the same PSTN provider or Local Gateway, and a location's main number cannot be moved.Manage phone numbers in Control Hub · Manage phone numbers in Control Hub > Move numbers between locations · Checked 2026-09-24
- 25A Control Hub location can be assigned only one PSTN option: Cisco Calling Plans, Cloud Connect, or on-premises PSTN via Local Gateway.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > PSTN connectivity · Checked 2026-09-24
- 26The Webex Calling 'Calls to On-Premises Extensions' setting is enabled per location and routes calls from that location's users to unknown extensions of 2 to 10 digits to a selected route group or trunk as premises calls.Configure trunks, route groups, and dial plans for Webex Calling · Configure trunks, route groups, and dial plans > Calls to On-Premises Extensions · Checked 2026-09-24
- 27If extension ranges overlap across sites, Cisco says an enterprise numbering plan must be created by prefixing extensions with an access code and a site code.Design to migrate from Unified CM to Webex Calling · Design to migrate > Webex Calling dial plan · Checked 2026-09-24
- 28Cisco describes the coexistence phase of a Unified CM to Webex Calling migration as one in which some users, devices and soft clients have moved to Webex Calling while others remain on on-premises Unified CM call control.Introduction (Migrate Unified CM to Webex Calling) · Introduction > Migration approach · Checked 2026-09-24
- 29Cisco states an organization may remain in the coexistence dual call control phase for an extended period of months or even years.Introduction (Migrate Unified CM to Webex Calling) · Introduction > Migration approach · Checked 2026-09-24
- 30Cisco names two migration approaches, flash-cut (all users and devices moved at the same time) and phased, and says most organizations use the phased approach.Introduction (Migrate Unified CM to Webex Calling) · Introduction > Migration approach · Checked 2026-09-24
- 31Phones on Unified CM that are being migrated must run phone load version 14.1 or later.Migrate Unified CM data to Webex Calling · Migrate Unified CM data to Webex Calling > Before you begin · Checked 2026-09-24
- 32Cisco Calling Plan ports activate automatically at the FOC time; allow at least 15 minutes, or 30 for project or complex ports, before numbers work.Cisco Calling Plan number porting guidelines and policies · Cisco Calling Plan number porting guidelines and policies > Port activation · Checked 2026-09-24
- 33For Cisco Calling Plan ports, the customer can change or cancel a port order in Control Hub before the losing carrier gives FOC; after FOC, changes need a support case with Cisco PSTN Technical Services.Cisco Calling Plan number porting guidelines and policies · Cisco Calling Plan number porting guidelines and policies > Modifying port orders · Checked 2026-09-24
- 34Cisco lists porting challenges including coordinating port orders precisely, potential delays, and provider limits such as a cap on concurrent port requests.Design to migrate from Unified CM to Webex Calling · Design to migrate > PSTN · Checked 2026-09-24
- 35Cisco says number porting can be done as a single coordinated cutover once the Webex Calling migration is complete, or incrementally per location as users move.Design to migrate from Unified CM to Webex Calling · Design to migrate > PSTN · Checked 2026-09-24
- 36Per the 2018 Hybrid Message guide, Jabber users see Webex App users' presence through the message connector, which polls Webex for all users' presence every 10 minutes.Deployment Guide for Hybrid Message - Cisco Webex Hybrid Message Service Overview · Hybrid Message Service Overview > Presence of Webex App, as Seen by Jabber User · Checked 2026-09-24
- 37Cisco's 2018 Hybrid Message deployment guide states that presence is not translated from Jabber to Webex App.Deployment Guide for Hybrid Message - Cisco Webex Hybrid Message Service Overview · Hybrid Message Service Overview > Presence of Jabber Client, as Seen by Webex App User · Checked 2026-09-24
- 38The transition dial plan must carry PSTN calls from Webex Calling via on-premises PSTN when that is used, and PSTN calls from Unified CM via Webex Calling when PSTN trunking for hybrid deployments is used.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (bulleted list of transition requirements) · Checked 2026-09-24
- 39Cisco describes retaining on-premises PSTN throughout the transition, with PSTN migrated per location as users move, as one option; Webex Calling users then use on-premises PSTN through the Local Gateway connection.Design to migrate from Unified CM to Webex Calling · Design to migrate > PSTN · Checked 2026-09-24
- 40Cisco's implementation checklist says to disable or delete the user and device directory number and calling features on Unified CM after the user has transitioned to Webex Calling.Implement the migration from Unified CM to Webex Calling · Implement the migration > user batch migration checklist · Checked 2026-09-24
- 41Hybrid PSTN trunking requires an add-on Webex Calling Route List Calls license, which allows 20% bursting above licensed call volume before non-emergency calls are blocked.PSTN trunking for hybrid Webex Calling deployments · PSTN trunking for hybrid Webex Calling deployments > licensing · Checked 2026-09-24
- 42In hybrid PSTN trunking each route list is assigned to a single location, and the calling number sent by the on-premises system must match an E.164 number configured in Webex Calling.PSTN trunking for hybrid Webex Calling deployments · PSTN trunking for hybrid Webex Calling deployments > requirements / route lists · Checked 2026-09-24
- 43Each Webex Calling location's routing prefix must be unique, and the routing prefix length can be 1 to 7 digits.Configure your Webex Calling dial plan · Configure your Webex Calling dial plan > Location Routing Prefix Length · Checked 2026-09-24
- 44In Cisco's migration design, all site codes of all locations must be unique and have the same length.Design to migrate from Unified CM to Webex Calling · Design to migrate > Locations · Checked 2026-09-24
- 45Because a Unified CM directory number out-matches the wildcarded Webex Calling route pattern, a migrated user's number left configured on Unified CM would likely keep calls from Unified CM callers on Unified CM instead of reaching the user on Webex Calling.inferredDesign to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (best match paragraph); combined with Implement > post-migration step to disable/delete DNs on Unified CM · Checked 2026-09-24
- 46For unknown-extension handling, Standard Behavior is the default and recommended option for PBX interoperability, while Legacy Behavior exists for backward compatibility and is not recommended when dial plans are configured.Configure trunks, route groups, and dial plans for Webex Calling · Configure trunks, route groups, and dial plans > Calls to On-Premises Extensions · Checked 2026-09-24
- 47In Cisco's migration design, no extension range may start with the inter-site steering digit or the PSTN steering digit.Design to migrate from Unified CM to Webex Calling · Design to migrate > Webex Calling dial plan · Checked 2026-09-24
- 48The Control Hub Unified CM migration tool migrates at most 1000 users and 1000 devices per task; larger migrations need multiple tasks.Migrate Unified CM data to Webex Calling · Migrate Unified CM data to Webex Calling > Before you begin · Checked 2026-09-24
- 49The Unified CM export/import migration covers auto attendants, devices, configured lines, device layout including shared lines, virtual lines, call queues, hunt groups, call park and user call forwarding and monitoring.Migrate devices and features from Unified CM to Webex Calling · Migrate devices and features from Unified CM to Webex Calling > supported features list · Checked 2026-09-24
- 50The Unified CM transition dial plan must also support abbreviated inter-site dialing and forced on-net dialing from Unified CM to Webex Calling.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (bulleted list of transition requirements) · Checked 2026-09-24
- 51Cisco's example calling search space for calls arriving from Webex includes partitions for +E.164 directory numbers (DN), abbreviated inter-site dialing (ESN) and PSTN access (PSTNInternational).Configure Unified CM for Webex Calling · Create a Calling Search Space for Calls From Webex · Checked 2026-09-24
- 52During the transition the Unified CM dial plan must support +E.164 dialing to Webex Calling and extension dialing to Webex Calling, intra-site and also inter-site when extension ranges are unique.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (bulleted list of transition requirements) · Checked 2026-09-24
- 53Cisco's Unified CM configuration adds abbreviated inter-site dialing normalization for Webex destinations, translating enterprise numbers to +E.164 before routing to the Webex partition.Configure Unified CM for Webex Calling · Configure Abbreviated Intersite Dialing Normalization for Webex · Checked 2026-09-24
- 54In Cisco's Unified CM configuration for Webex Calling, the SIP trunk to the Local Gateway uses port 5065 so Webex-bound traffic can be told apart from PSTN traffic (port 5060) to the same device.Configure Unified CM for Webex Calling · Configure SIP Trunk Security Profile for Trunk to Local Gateway · Checked 2026-09-24
- 55Webex Calling cannot integrate with a premises-based voicemail system such as Unity Connection or Unity Connection Express.Prepare to migrate from Unified CM to Webex Calling · Prepare to migrate > Cisco integrations: Unity Connection UCCX UCCE · Checked 2026-09-24
- 56During coexistence an organization will likely run two voicemail systems, Webex Calling native voicemail for migrated users and Unity Connection for users still on Unified CM, since Webex Calling cannot use Unity Connection.inferredPrepare to migrate from Unified CM to Webex Calling · Prepare to migrate > Cisco integrations: Unity Connection UCCX UCCE · Checked 2026-09-24
- 57Webex Calling dial plans are configured globally for the enterprise and apply to all users regardless of location; they route matching calls to on-premises destinations over a trunk or route group.Configure trunks, route groups, and dial plans for Webex Calling · Configure trunks, route groups, and dial plans > Dial plans · Checked 2026-09-24
- 58When on-premises call control is integrated, Webex Calling enterprise dial plans should contain only the patterns needed to route calls to on-premises destinations.Implement the migration from Unified CM to Webex Calling · Implement the migration > Integration with on-premises call control · Checked 2026-09-24
- 59Cisco's coexistence design adds a Webex Calling partition to the Unified CM dial plan containing +E.164 route patterns for all Webex Calling destinations.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM · Checked 2026-09-24
- 60In the reverse direction the transition dial plan must support forced on-net dialing and inter-site extension dialing from Webex Calling to Unified CM.Design to migrate from Unified CM to Webex Calling · Design to migrate > On-premises dial plan in Unified CM (bulleted list of transition requirements) · Checked 2026-09-24
Documents
Cisco Calling Plan number porting guidelines and policies
Configure trunks, route groups, and dial plans for Webex Calling
Configure Unified CM for Webex Calling
Configure Webex Calling Customer Assist for Unified Communications Manager
Configure your Webex Calling dial plan
Deployment Guide for Hybrid Message - Cisco Webex Hybrid Message Service Overview
Design to migrate from Unified CM to Webex Calling
Implement the migration from Unified CM to Webex Calling
Introduction (Migrate Unified CM to Webex Calling)
Manage phone numbers in Control Hub
Migrate devices and features from Unified CM to Webex Calling
Migrate Unified CM data to Webex Calling
Prepare to migrate from Unified CM to Webex Calling
PSTN trunking for hybrid Webex Calling deployments
Upgrade Jabber with IM and Presence to Webex App
Cite this page
APA
WarmTransfer. (2026, September 24). Unified CM and Webex Calling coexistence during a migration. WarmTransfer. https://warmtransfer.net/knowledge/cucm-webex-calling-coexistence
BibTeX
@misc{warmtransfer-cucm-webex-calling-coexistence,
title = {Unified CM and Webex Calling coexistence during a migration},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/cucm-webex-calling-coexistence},
note = {Verified 2026-09-24}
}