Microsoft 365 Alert : Service Degradation – Microsoft Teams – Some users may be unable to make or receive Public Switched Telephone Network (PSTN) calls in Microsoft Teams – RESOLVED

Announcements Sourav Nandi

13/10/2022 14:05:00 PM (BST)

NHSmail Reference : INC32126034

Microsoft Reference : TM445531

Issue Status : RESOLVED

Issue Description : Some users may have been unable to make or receive Public Switched Telephone Network (PSTN) calls in Microsoft Teams.

More info : Users may also have been unable to utilize Direct Routing or Operator Connect to execute PSTN calls.

Scope of impact : Impact was specific to some users who are served through the affected infrastructure in Europe, Middle East, and Africa.

Final Update : 13/10/2022 16:40:00 PM – Microsoft has successfully rerouted user requests to alternate healthy infrastructure, and confirmed impact has been remediated after a period of monitoring.

Root cause : An unexpected Transport Layer Security error in a section of infrastructure responsible for serving user traffic, prevented users from making or receiving PSTN calls in Microsoft Teams.

Next steps : Microsoft is analyzing traffic data and Transport Layer Security error logs on the affected infrastructure to help prevent this problem from happening again.