Microsoft Teams Calling blocked "We couldn't complete the call. Please contact your admin"

Occasional Reader

On a relatively new (3 weeks old) tenant, set up cleanly, with paid subscriptions and proper, correct licensing for Teams Calling, PSTN calling has been working fine since implementation.

 

But last night I received multiple emails stating "Skype for Business all users blocked for PSTN calling - We have detected what may be fraudulent calling activity for one or more of your Skype for Business users. In order to prevent financial risk to you and your business we have disabled calling and/or conferencing services for all users:"

 

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I got an email for each user, AND an email stating that ALL users were blocked.

 

This is a brand new tenant in Teams-only mode, SkypeForBusiness doesn't even show up in the tenant. There is no "Reports->Skype for Business->ANYTHING" option in the M365 Admin Center.

 

Entra Admin Center shows no logins or unknown activity for any of the users (all of which are protected with 2FA and authenticators). The Teams Admin Center Usage Report shows only two calls made in the past 24 hours - both were test calls from me to my cell testing out call forwarding. The Teams Admin Center Blocked Users Report is broken and crashing.

 

I tried to test with the self-help diagnostics. Interestingly, the diagnostic fails saying there is no number assigned to the user...

 

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Except that there is. In the assigned numbers screen, everything shows up properly and correctly.

 

The emails state: "If you determine the call(s) were not fraudulent, please: Contact Microsoft Support. A customer support agent will assist you in unblocking the user’s calling and/or conferencing capabilities."

 

The problem is that the support engineers I'm getting are on the other side of the planet, with an accent very different than mine. They can barely understand me and I can barely hear them. Worse: they kept attempting to debug using Get-CsUser - which is a fully-deprecated and no-longer-working cmdlet, and then basically gave up, saying they would "escalate it to their back office."  They have no idea what is happening or why or how to fix it.

 

I've had no updates since.

 

Does anyone know why this happened or how to fix it? No fraudulent logins, no compromised accounts, no strange calls, no nothing... and yet the entire tenant is blocked? I've gone through most of the PowerShell cmdlets I can think of, compared them against a working tenant, and they're all identical - yet both incoming and outgoing PSTN calling remains blocked.

 

Can anyone help me either fix this, or teach me how to get past the front-line support at Microsoft to someone who knows how to unblock this?

 

My users are already looking at Google Voice... ugh...

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