Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users can’t connect to some meetings via Public Switched Telephone Network (PSTN) connections in Microsoft Teams – RESOLVED

09/06/2023 09:40:00 AM (GMT)

NHSmail Reference : INC36301554

Microsoft Reference : TM577686

Issue Status : RESOLVED

Issue Description : Users can’t connect to some meetings via Public Switched Telephone Network (PSTN) connections in Microsoft Teams.

More info : This issue specifically impacts recurring meetings created between March 1, 2023, and May 22, 2023. Meetings created outside that date range are unaffected. Impacted meetings are 60+ days old.

Where possible, affected users can bypass impact by joining the affected meeting via Microsoft Teams or leveraging the PSTN dial-out feature.

Additionally, the user that created an affected meeting can mitigate impact to that meeting manually by rescheduling the meeting to any date and time, including to the date and time already set.

Final Update : 13/06/2023 08:50:00 AM – Microsoft reverted the offending update to fix this issue, but meetings created during the impact period were still affected. They received a list of these meetings from your representatives and have manually repaired the expiration time where applicable. A subset of meetings could not be modified and may still be impacted. These meetings can be repaired by the user that created them by following the instructions listed in the More Info section above and need confirmation from your representatives in order to validate impact remediation. They have been unable to reach your organization’s representatives to validate that the corrective actions resolved the issue. In the event impact persists, please contact one of the support representatives so Microsoft can continue our investigation into the problem.

Scope of impact :Your organization is affected by this event, and any user attempting to access an affected meeting that’s over 60 days old via a PSTN connection is impacted.

Root cause : An update to the Microsoft Teams infrastructure responsible for handling meeting permissions, intended to improve PSTN functionality, contained a regression that caused PSTN access attempts to fail for meetings older than 60 days, resulting in impact.

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