PSTN calls - voice drops out, but call still connected

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Regular Contributor

Office 365/Phone System/Domestic Calling plan in US. Teams Only mode now, (however this was  happening in Islands as well). Not using direct routing. Not behind a proxy. Testing PSTN for a tenant setup with a single user and this is about as simple as setup as I can imagine.

 

When I receive or place calls, some time into the call the other party can no longer hear me. I can still hear them, however. The call doesn't drop. I'm forced to end the call, and either call the party back or wait for them to call me, after which point it works again for a while. There are no obvious LAN problems here or issues with my ISP - my network connection is stable, reasonably fast (400/20), low-latency, acceptable buffer-bloat, and there are no ISP outages in either direction. There's no other significant activity on the network.

 

This happens on a variety of devices - from the Teams app on Windows using either the built-in mic/speaker, from a USB headset, and also from Polycom VoIP phones. All wired ethernet. It's a very regular occurrence.

 

I just had it happen and checked the call quality log, and the report was that it was a "good call" that ended normally, no packet loss, no excessive latency or jitter. I'm not familiar with the deeper logging data at the debug level to know whether there's a clue there.

 

Any advice before resorting to submitting a support ticket? Also, what's the community consensus as to the reliability of MS Phone System for basic voice calling (i.e., ignoring more advanced PBX features for now)? 

 

Thanks as always,

Bob

1 Reply

I would suspect something related to network or firewalls that starts effecting the media packets in some way.