SIP devices can't make or receive calls

Title: SIP devices can't make or receive calls User impact: Users may be unable to make or receive call using SIP devices. Final status: We've determined that this issue is a duplicate of another event. Please look for further updates in TM1519335. This communication will expire in 24 hours. This is the final update for the event.

Title: SIP devices can't make or receive calls User impact: Users may be unable to make or receive call using SIP devices. More info: Once a SIP device attempts to perform its next synchronization, the device will disconnect. Users will be unable to log back into those devices and therefore can't make or receive calls using those SIP devices. Calling functionality using the Microsoft Teams web and desktop clients, or Teams Phone Devices are not impacted. Current status: We’ve identified the underlying root cause and we are working on developing a fix. Scope of impact: This issue could impact any SIP device. Next update: Wednesday, October 21, 2026 at 11:00 PM UTC