11 · TLS, certificates, SIP
OPTIONS are how Teams decides the trunk is willing. A dial plan cannot heal a trunk that does not answer.
Teams sends SIP OPTIONS to the SBC. The SBC should answer while it is in service. The admin center shows SBC status from that health. This campus does not pretend to know Microsoft’s private failure counter. Repeated misses are a reason to pull the trunk from the route and look at the log.
Answer on the signaling interface, not the management port. Rehearse a failure. A second gateway that has never seen an INVITE is untested.
SIP OPTIONS tell you the SBC is alive. Pull a trunk that keeps missing them, and do not invent a magic counter.
I treat missed OPTIONS as a trunk problem and I look at the admin-center status beside the SBC log.
If it fails: A script fails over on a single lost packet and flaps the trunk all day.
A colleague reports: The chain is trusted and the EKU is still wrong. Where do you start?
The chain is trusted and the EKU is still wrong. Request the certificate from the SBC’s CSR so the name and the EKU are right. Source: https://learn.microsoft.com/en-us/microsoftteams/direct-routing-plan accessed 2026-10-14.
Which description of DTMF relay is accurate?
Digits in the audio path or as telephone-events. IVRs fail when the SBC strips them. A human can talk and the bot never hears 1. Source: https://learn.microsoft.com/en-us/microsoftteams/direct-routing-plan accessed 2026-10-14.
A colleague reports: The queue escape works in the lab and fails through the carrier. Where do you start?
The queue escape works in the lab and fails through the carrier. Test digits through every SBC, not only Teams-to-Teams. Source: https://learn.microsoft.com/en-us/microsoftteams/direct-routing-plan accessed 2026-10-14.
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.
A script fails over on a single lost packet and flaps the trunk all day.
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.
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.
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.
Copilot Studio, Azure Communication Services, and Graph are later tracks in this lab. Treat any uncited limit as confirm before relying.
Opened 2026-10. A row marked confirm did not open. Wikipedia is background. The Teams blog row is the community index.
