Answering external calls disconnects

Hi All,

We're experiencing intermittent issues with our Teams at the moment.

When answering an incoming external call there's silence on our end and then the call just disconnects; it happens intermittently so can't quite pin down what is causing this.

Calling internally to teams contacts works fine, and we can even make calls to external numbers.

I've tested calling our number from my mobile, it rings just fine, but when I answer it on Teams, my mobile pauses for a split second then a different calling tone starts (I can even see the call timer start counting on my mobile), after a couple seconds it drops out.

This has started happening this week, which seems to have coincided with a recent Teams update, not sure if this caused the issue though, but it is suspicious.
Our teams version is: Version 1.4.00.16575 (64-bit)

Happens on Windows 10 PC as well as our phones Yealink T58A

Is anyone else experiencing this issue/knows of a solution?

Thanks

Edit:
Signing out of Teams and signing back in again temporarily resolves the issue. But after a few minutes it reverts back to dropping the call.