Moving from Unified CM to Zoom Phone

See also

Sources

1. 1
   For BYOC numbers, admins can submit emergency address data by CSV for carrier verification, and Zoom tracks a 'Carrier Update Required' status until the carrier has validated the new address.

   Setting up emergency addresses · BYOC numbers section · Checked 2026-09-25
2. 2
   For US and Canada BYOC numbers, Zoom lets the admin choose whether emergency calls go through the BYOC carrier or through Zoom ('Target Carrier for routing emergency calls placed by BYOC numbers'); for BYOC numbers outside the US and Canada the carrier is fixed.

   Routing emergency calls · BYOC emergency carrier setting · Checked 2026-09-25
3. 3
   When an SBC is set to BYOC-P, both the calling and the called numbers on calls from Zoom to the SBC must be in E.164 format.

   BYOC-P or BYOP-P configuration guide · Session Border Controllers section, BYOC-P option · Checked 2026-09-25
4. 4
   Route groups enabled for BYOC-P are for third-party PSTN interoperability and do not support a private numbering plan.

   BYOC-P or BYOP-P call processing · Introductory section · Checked 2026-09-25
5. 5
   If no interoperability with a legacy PBX is required, only BYOC-P needs to be enabled at the SBC and route group level.

   BYOC-P or BYOP-P call processing · Introductory section · Checked 2026-09-25
6. 6
   BYOC numbers already in Zoom can later be moved to Zoom native service by a BYOC-to-native port, which is requested through Zoom Support with a signed LOA, a recent bill and a BYOC porting sheet.

   Requesting a BYOC number port · Definition and request steps · Checked 2026-09-25
7. 7
   Zoom Phone endpoints always initiate connections to Zoom data centres, but BYOP SBCs require bidirectional connectivity.

   Migration Strategies (Zoom Phone Bluepaper) · Bring Your Own PBX section · Checked 2026-09-25
8. 8
   Zoom's migration guidance says that with BYOP, when a user dials an extension, the relevant PBX automatically queries both the on-premises PBX and Zoom Phone for the user with that extension.

   Migration Strategies (Zoom Phone Bluepaper) · Bring Your Own PBX section · Checked 2026-09-25
9. 9
   BYOP-P calls may use localized or E.164 numbers up to 24 digits, whereas BYOC-P calls use E.164 in the Request-URI user part.

   BYOC-P or BYOP-P call processing · Outbound calls from Zoom and Incoming calls to Zoom sections, Request-URI · Checked 2026-09-25
10. 10
    Bring Your Own PBX - Premises (BYOP-P) connects a customer-administered session border controller to Zoom Phone so that an existing on-premises PBX can interwork with Zoom Phone.

    BYOC-P or BYOP-P deployment and connectivity options · Introduction / definitions of BYOC-P and BYOP-P · Checked 2026-09-25
11. 11
    In the Zoom SBC configuration, the BYOP-P option enables extension-based dialling between Zoom Phone and an on-premises PBX through an SBC.

    BYOC-P or BYOP-P configuration guide · Session Border Controllers section, BYOP-P option · Checked 2026-09-25
12. 12
    On outbound calls Zoom populates calling name and number in the Contact and P-Asserted-Identity headers and does not use Remote-Party-ID; on inbound calls it accepts calling identity in RPID as well as PAI and From.

    BYOC-P or BYOP-P call processing · Outbound calls from Zoom and Incoming calls to Zoom sections, caller ID · Checked 2026-09-25
13. 13
    Zoom supports up to 47 bytes for caller names in SIP fields on BYOC-P/BYOP-P calls.

    BYOC-P or BYOP-P call processing · Caller ID paragraph · Checked 2026-09-25
14. 14
    Zoom maintains a separate list of certified SBC vendors and models that have passed interoperability testing for BYOC-P/BYOP-P; the infrastructure requirements page links to it rather than listing them.

    BYOC-P or BYOP-P infrastructure requirements · SBC requirements, certified SBC reference · Checked 2026-09-25
15. 15
    As accessed, Zoom lists supported firmware 12.0(7)SR5 for the Cisco 7841 and 8851, 12.0(7)SR2 for the 8845 (which is flagged EOL), and 4.1(1)SR1 for the 9861, each with firmware date 7/19/2026 and ZTP enabled.

    Zoom Phone certified hardware · Cisco table, rows 7841, 8845, 8851, 9861 · Checked 2026-09-25
16. 16
    Zoom's certified hardware page lists Cisco MPP models including the 6821, 6851, 6861, 6871, 7811, 7821, 7832, 7841, 7861, 8811, 8832, 8841, 8845, 8851, 8861, 8865, 9841, 9851, 9861 and 9871.

    Zoom Phone certified hardware · Cisco table, model column · Checked 2026-09-25
17. 17
    Zoom Phone supports only Cisco Multiplatform (MPP) phones, identified by 3PCC, 3PC or 3PW after the model number; Cisco phones running Enterprise (Unified CM) firmware are not supported.

    Zoom Phone certified hardware · Cisco section, introductory note · Checked 2026-09-25
18. 18
    If Unified CM sends delayed-offer INVITEs toward the SBC, the SBC (or an MTP in Unified CM) must convert them to early offer before they reach Zoom.inferred

    BYOC-P or BYOP-P call processing · Incoming calls to Zoom section (early offer requirement) · Checked 2026-09-25
19. 19
    Cisco says that for new phone orders the correct workflow is to buy the SKU for the target deployment (MPP or Enterprise) rather than buy one type and convert.

    Convert Cisco 7800 and 8800 series IP phones between Enterprise and MPP Firmware · Conversion purpose note · Checked 2026-09-25
20. 20
    Cisco 8821 and 8831 phones are not eligible to convert from Enterprise to MPP firmware.

    Convert Cisco 7800 and 8800 series IP phones between Enterprise and MPP Firmware · Key caveats, ineligible models · Checked 2026-09-25
21. 21
    Converting Cisco 7800 or 8800 phones from Enterprise to MPP firmware for a non-Webex call control platform requires a per-device migration licence (L-CP-E2M-78XX-CNV= or L-CP-E2M-88XX-CNV=) that is node-locked to the phone's MAC address; conversion for Webex Calling carries no licence cost.

    Convert Cisco 7800 and 8800 series IP phones between Enterprise and MPP Firmware · License requirements section · Checked 2026-09-25
22. 22
    Before conversion, Cisco requires phones to be on Enterprise firmware 14.2.1SR1 or later, and converted 8800 audio phones with hardware version V15 or later need at least MPP firmware 11.3.3.

    Convert Cisco 7800 and 8800 series IP phones between Enterprise and MPP Firmware · Minimum firmware requirements; models eligible section · Checked 2026-09-25
23. 23
    Zoom requires the SBC to send INVITEs with an SDP offer (early offer), and Zoom's own outbound INVITEs also carry the SDP offer.

    BYOC-P or BYOP-P call processing · Incoming calls to Zoom and Outbound calls from Zoom sections · Checked 2026-09-25
24. 24
    Zoom Phone emergency addresses can be set in any country or region, even where Zoom Phone does not offer direct numbers.

    Setting up emergency addresses · Emergency address country note · Checked 2026-09-25
25. 25
    Zoom Phone can route emergency calls to the PSAP (9-1-1 when the emergency address is in the US or Canada), to an internal safety response team, to both in parallel, or to the safety team first and then the PSAP if unanswered.

    Routing emergency calls · Emergency call routing options · Checked 2026-09-25
26. 26
    Zoom sends a call to a backup SBC when the primary is marked down by OPTIONS keepalive failure or answers Zoom's INVITE with 403, 408, 480, 488, 500, 502, 503, 504 or 606; when a route group is exhausted it moves to SBCs in the backup region or data centre.

    BYOC-P or BYOP-P call processing · Failover section · Checked 2026-09-25
27. 27
    For a hybrid deployment with a legacy PBX, Zoom says to enable the SBC for both BYOC-P and BYOP-P, and to point Zoom external contacts and routing rules at a SIP Group containing BYOP-P-enabled route groups so the private dial plan extends to Zoom.

    BYOC-P or BYOP-P call processing · Introductory section · Checked 2026-09-25
28. 28
    BYOC-P and BYOP-P connections over the internet are protected with TLS 1.2 signalling and SRTP media.

    BYOC-P or BYOP-P infrastructure requirements · SBC requirements list · Checked 2026-09-25
29. 29
    Zoom's article 'Setting up Cisco Unified Communications Manager (CUCM) with Zoom' configures a Unified CM SIP trunk to VCS Control or Expressway-C, and the benefit it states is dual-stream content and better meeting quality.

    Setting up Cisco Unified Communications Manager (CUCM) with Zoom · Sections: SIP trunk security profile; SIP profile; SIP trunk to VCS; neighbor zone · Checked 2026-09-25
30. 30
    Zoom's 'CUCM with Zoom' article is a video and meetings interop guide, not a Zoom Phone BYOP-P coexistence guide, so it should not be cited for Unified CM to Zoom Phone call routing.inferred

    Setting up Cisco Unified Communications Manager (CUCM) with Zoom · Whole article: trunk target is VCS/Expressway-C; no mention of BYOP-P, route groups or SIP groups · Checked 2026-09-25
31. 31
    On calls into Zoom, Zoom supports PRACK for early media but does not use SIP preconditions or the Replaces header.

    BYOC-P or BYOP-P call processing · Incoming calls to Zoom section · Checked 2026-09-25
32. 32
    Zoom marks an SBC failed after four consecutive OPTIONS keepalive failures, which takes 90 to 120 seconds in total to detect.

    BYOC-P or BYOP-P call processing · Failover section, keepalive · Checked 2026-09-25
33. 33
    Zoom suggests that customers migrating without a partner or Zoom Professional Services may use a phased approach, moving users one site at a time or in percentage increments such as 5% per day or week.

    Migration Strategies (Zoom Phone Bluepaper) · A Phased Approach section · Checked 2026-09-25
34. 34
    Desk phones must support TLS 1.2 to work with Zoom Phone.

    Zoom Phone certified hardware · Security requirements note · Checked 2026-09-25
35. 35
    Through the Zoom web portal, up to 100 US, Canada or Puerto Rico numbers can be ported per request.

    Requesting a number port for US, Canada, or Puerto Rico · Port request steps · Checked 2026-09-25
36. 36
    Zoom says to allow 3 to 5 business days for a response from the losing carrier to a US, Canada or Puerto Rico port request.

    Requesting a number port for US, Canada, or Puerto Rico · After submission section · Checked 2026-09-25
37. 37
    Zoom advises pre-assigning numbers that are being ported, to users or other destinations, before the port date so the transition is smooth.

    Requesting a number port for US, Canada, or Puerto Rico · Port activation / pre-port preparation note · Checked 2026-09-25
38. 38
    The activation time for US and Canada number ports into Zoom is fixed at 11:30 AM Eastern Time and cannot be changed.

    Requesting a number port for US, Canada, or Puerto Rico · Port activation note · Checked 2026-09-25
39. 39
    BYOC-P or BYOP-P over private circuits uses dedicated SIP trunks to one or more Zoom data centres in a region and requires BGP peering between Zoom and the customer; private circuits are arranged through the Zoom account team.

    BYOC-P or BYOP-P deployment and connectivity options · Private circuits section · Checked 2026-09-25
40. 40
    Zoom Phone Provider Exchange brings a customer's own carrier into Zoom Phone through cloud peering, with no on-premises hardware, and is set up from Number Management > Provider Exchange in the Zoom web portal.

    Setting up Phone provider exchange · Overview and setup steps · Checked 2026-09-25
41. 41
    Provider Exchange by itself does not give Unified CM extension-dialling interop with Zoom Phone; that needs a premises SBC with BYOP-P.inferred

    BYOC-P or BYOP-P call processing · Introductory section (BYOP-P on SBC and route group) · Checked 2026-09-25
42. 42
    Zoom Professional Services migration support includes a hypercare period of 10 days of post-go-live support.

    Migration Strategies (Zoom Phone Bluepaper) · Professional Services section · Checked 2026-09-25
43. 43
    Zoom's BYOC-P/BYOP-P call processing article states that on outbound calls from Zoom, Zoom supports PRACK for reliable 1xx responses but does not use REFER or SUBSCRIBE/NOTIFY.disputed

    BYOC-P or BYOP-P call processing · Outbound calls from Zoom section · Checked 2026-09-25
44. 44
    The Zoom SBC configuration offers an option to allow REFER support for call transfer, applicable to Zoom Phone only.disputed

    BYOC-P or BYOP-P configuration guide · SBC configuration capabilities, 'Allow REFER support to transfer calls (Zoom Phone only)' · Checked 2026-09-25
45. 45
    Creating a BYOC-P/BYOP-P route group in Zoom can take up to 48 hours to complete.

    BYOC-P or BYOP-P configuration guide · Route Groups section · Checked 2026-09-25
46. 46
    A Zoom route group distributes calls across its SBCs either sequentially, starting with the first SBC in the list, or by load balancing according to the proportion assigned to each SBC.

    BYOC-P or BYOP-P configuration guide · Route Groups section, distribution method · Checked 2026-09-25
47. 47
    The SBC must present a certificate from one of Zoom's listed certificate authorities, with the SBC FQDN in the CN or SAN, the Server Authentication key usage, and the complete chain including intermediates.

    BYOC-P or BYOP-P infrastructure requirements · Certificate requirements section · Checked 2026-09-25
48. 48
    Zoom lists Opus, G.722, G.711 µ-law, G.711 A-law and G.729 as the codecs for BYOC-P/BYOP-P SBCs.

    BYOC-P or BYOP-P infrastructure requirements · SBC requirements list, codec support · Checked 2026-09-25
49. 49
    To change an SBC's IP address in Zoom, the SBC must be deleted and re-added.

    BYOC-P or BYOP-P configuration guide · SBC deletion and IP changes · Checked 2026-09-25
50. 50
    BYOC-P/BYOP-P signalling uses TCP 5061 and media uses UDP 10000 to 64000, both bidirectional between the SBC and Zoom.

    BYOC-P or BYOP-P infrastructure requirements · IP ranges and ports section · Checked 2026-09-25
51. 51
    Zoom requires a BYOC-P/BYOP-P SBC to support SIP per RFC 3261, DTMF per RFC 2833, topology hiding per RFC 5853, and early offer on INVITEs sent to Zoom.

    BYOC-P or BYOP-P infrastructure requirements · SBC requirements list · Checked 2026-09-25
52. 52
    The transport between Zoom and a BYOC-P/BYOP-P SBC is TLS only, and the setting cannot be changed.

    BYOC-P or BYOP-P configuration guide · Session Border Controllers section, protocol field · Checked 2026-09-25
53. 53
    Zoom SIP Groups attach entities such as phone numbers, external contacts, routing rules and emergency service customisations to route groups, and calls to or from those entities use the SIP Group's route groups; Zoom presents this as a way to phase migration.

    BYOC-P or BYOP-P configuration guide · SIP Groups section · Checked 2026-09-25
54. 54
    Zoom does not accept SDP offers or media streams that specify an SRTP Master Key Identifier (MKI).

    BYOC-P or BYOP-P infrastructure requirements · Operational notes, SRTP MKI · Checked 2026-09-25
55. 55
    A Zoom Phone SBC setting enables T.38 negotiation for fax calls; when it is disabled, fax calls use G.711 passthrough only.

    BYOC-P or BYOP-P configuration guide · SBC settings, 'Use T.38 protocol for faxing' · Checked 2026-09-25
56. 56
    Zoom describes three primary Zoom Phone PSTN service offerings: Zoom Phone Native, Bring Your Own Carrier with Cloud Peering (BYOC-C), and Bring Your Own Carrier with Premises Peering (BYOC-P).

    Overview | Zoom Technical Library · Overview section · Checked 2026-09-25
57. 57
    URI dialling is not supported on BYOC-P/BYOP-P trunks; calls into Zoom must carry E.164 SIP URIs, or digit strings for BYOP-P.

    BYOC-P or BYOP-P call processing · Incoming calls to Zoom section · Checked 2026-09-25
58. 58
    Zoom Phone Local Survivability (ZPLS) is an on-premises virtual appliance that connects internal calls between users in a site when Zoom data centres are unreachable, and it can integrate with an SBC to make and receive PSTN calls during that outage.

    Zoom Phone Local Survivability (Zoom Phone Bluepaper) · Zoom Phone Local Survivability section · Checked 2026-09-25

Documents

Cite this page

WarmTransfer. (2026, September 25). Moving from Unified CM to Zoom Phone. WarmTransfer. https://warmtransfer.net/knowledge/cucm-to-zoom-phone

@misc{warmtransfer-cucm-to-zoom-phone,
  title  = {Moving from Unified CM to Zoom Phone},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/cucm-to-zoom-phone},
  note   = {Verified 2026-09-25}
}