Voice LabTeams Phone

14 · Coexistence and CCaaS

Webex calling interop

A split estate needs a voice bridge. Chat federation is a different project.

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Learn it in 5 minutes

A SIP trunk through a local gateway or CUBE can carry calls between Webex Calling users and Teams users. Treat it as coexistence with one numbering plan. Two dial plans that both own a range will fail in both directions.

Do not describe that trunk as a merger, and do not assume meeting interop came along for free. Write which numbers remain on Webex and for how long.

Bridge Webex Calling and Teams with an SBC and one numbering owner. Keep chat interop as a separate decision.

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Visual

Call queue routingCall queueLongest idleAgent 1Agent 2Agent 3Timeout to overflow
Longest idle distribution for Webex calling interop. Overflow is a configured target.
SplitTeams ranges · NamedWebex ranges · NamedShared confusion · Avoid
Example, not a customer. Counts in this drawing are teaching order, not customers.

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Worked example

Webex voice interop is a SIP bridge and a numbering plan, not a chat project.

  1. Ranges Who owns which
  2. Trunk SBC between them
  3. Normalize One owner
  4. End date When the split stops

If it fails: Both clouds believe they own the same range.

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Quiz

A colleague reports: Early offer and codec preferences are left at a lab default and calls 488. Where do you start?

Which description of One normalization owner is accurate?

A colleague reports: CUCM adds a prefix and the Teams dial plan adds it again. Where do you start?

Flashcards

Ecosystem

Glossary

  • Connect model A certified contact center attaches to Teams through certified SBCs and Direct Routing. Config: Confirm the vendor’s current certification, then design the SBC and the transfer target’s license. Fault: Transfers to experts fail because the expert has no Teams Phone number.
  • Extend model The contact center uses the Teams client, Graph, and Cloud Communications APIs. Teams Phone is the calling system and the agent works in Teams. Config: Read the Extend section of the contact-center article before you license agents. Fault: The design buys a Connect SBC for an Extend product.
  • Unify model The model Microsoft Learn names, as of 14 October 2026, for a native experience. Partner material describes it as ACS-based applications on Teams calling infrastructure. Older decks say Power. Ask which current model a vendor holds. Config: Get the vendor’s certification letter and match it to Connect, Extend, or Unify. Fault: A proposal says Power and nobody can find the media path.
  • Teams Phone extensibility A way for a contact center, including Dynamics 365 Contact Center, to use a customer’s existing Teams Phone for the agent’s telephony. Config: Use a solution that has finished the certification if you want the supported experience. The API existing is not the same as a finished certification. Fault: Two phone systems ring the same person.

Sister technologies

Around the call: compliance recording, workforce management, emergency location, analytics, CRM screen pop, and an agent with a human escape. Each one has its own failure.

Config and troubleshooting

Both clouds believe they own the same range.

Cross-platform bridges

CUCM

Cisco CUBE is one of the SBC families named in this lab’s certification lesson. A certified release can be the Direct Routing SBC between Unified CM and Teams.

The tenant still needs a verified domain on the SBC FQDN, and the user still needs Teams Phone. The studio translator does not open a live AXL session. Confirm the current certified release before you build.

Webex

Teams Phone and Webex Calling are separate clouds. This lab does not describe a feature that registers a Webex Calling user into a Teams tenant.

A number move is usually a carrier port, a certified SBC, or a meetings interop product. Confirm before relying.

UCCE

Unified CCE stays the ACD until you migrate it. Microsoft’s contact-center articles name Connect, Extend, and Unify. They do not name a UCCE connector in the notes this lab cites.

Voice into Teams is still Direct Routing or Operator Connect. The routing script stays on the contact-center product you bought. Confirm the vendor’s current model. Source: https://learn.microsoft.com/en-us/microsoftteams/teams-contact-center.

Future hooks

Copilot Studio, Azure Communication Services, and Graph are later tracks in this lab. Treat any uncited limit as confirm before relying.

BridgesEcosystem

Sources and go deeper

Opened 2026-10. A row marked confirm did not open. Wikipedia is background. The Teams blog row is the community index.

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