Voice LabTeams Phone

10 · Session border controllers

The support boundary

Knowing who you call is part of the design.

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Learn it in 5 minutes

Collect the firmware, the paired FQDN, a ladder with Call-ID, and the OPTIONS history before you call. The vendor investigates. Microsoft may decline a case on a non-certified SBC.

Keep a screenshot of the certified list from the week you bought. A 2022 PDF in the project folder is how you discover you are unsupported during the outage.

Open SBC tickets with the vendor, the firmware, and a Call-ID. Keep the certification evidence.

Room HTML

Visual

Media bypass beside the signaling pathTeams clientMedia processorCertified SBCMedia bypass candidate, same site. Signaling still visits Teams.Signaling does not bypass
Two paths for The support boundary. RTP may skip the processor. SIP does not.
What the ticket needsFirmware · RequiredCall-ID · RequiredList date · Required
Minimum evidence. Counts in this drawing are teaching order, not customers.

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Worked example

Vendor first, with firmware and a Call-ID. I keep the certified-list date.

  1. Evidence Firmware, FQDN, ladder
  2. Vendor First call
  3. Escalate Only if they must
  4. List From the week you bought

If it fails: The outage call starts with no logs and an unlisted build.

Checklist HTML

Quiz

A colleague reports: A router with SIP ALG is described as the SBC. Where do you start?

Which description of SIP ALG is accurate?

A colleague reports: INVITEs are rewritten and the contact header points at a private address. Where do you start?

Flashcards

Ecosystem

Glossary

  • Early offer Teams Direct Routing presents media in the INVITE. An SBC or CUBE that waits for a delayed offer will negotiate badly. Config: Set the vendor profile for early offer toward Teams. Fault: CUCM sends delayed offer all the way to Teams.
  • AudioCodes A certified SBC family. Mediant devices and their management tools are common in Direct Routing designs. The Microsoft certified list is the support boundary, the vendor guide is the config. Config: Follow AudioCodes’ current Teams document for the firmware you run. Fault: A forum config from 2019 is pasted onto new firmware.
  • Ribbon SBC Ribbon’s certified session border controllers are a Direct Routing option. Core and software editions differ. Config: Use Ribbon’s current Teams guide and a public certificate. Fault: OPTIONS are answered on the wrong interface.
  • Oracle SBC Oracle Communications Session Border Controller can be certified for Direct Routing on specific releases. Check the Microsoft list for the release, not the logo. Config: Match the certified software version and the certificate name. Fault: The beautiful config is one release below the certified list.

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

The outage call starts with no logs and an unlisted build.

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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