PSTN Teams inbound calls keeps dropping

[iCobretti]

Hi all,

I have a problem with Teams Client app, when I receive PSTN calls Teams immediately drop it and I can't answer.

The stranger thing is that with web browser app (teams.microsoft.com) is working fine.

The steps I tried solving the issue are:

- Uninstall and reinstall Microsoft Teams app

- Clear Teams Cache in C:\users\userprofile\appdata\roaming\teams

- try to delete and then re-assign the calling plan license to my user in 365 admin center.

- verify the Teams policy applied to my account that are the same as other users where it works fine

Outbound calls works correctly.

I really don't know what to do.

Can you please help me?

Thanks a lot

Regards

Matteo

[#2]

@iCobretti Sounds like a network/firewall problem, are you allowing all the required ports, particularly the 3478-3481 range as described at Office 365 URLs and IP address ranges - Microsoft 365 Enterprise | Microsoft Learn

[#3]

Hi Steven,
thanks for your response.
I exclude network/fw issue because i'm in the office and my other colleagues, connected to the same network, do not have this problem.
And also, as i posted, with web app works normally

i don't know what to do

[#4]

@iCobretti 

• Are you using direct routing?
• If yes, what SBC are you using?
• If using direct routing, are you using media bypass?
• Is it all inbound calls drop?
• Is it an immediate drop, or is there a delay of a few seconds?
• Do you hear any audio on either side?

[#5]

@jangliss 

hi

yes i'm using direct routing and SBC like all my colleagues

is an immediate drop and the calls go immediately to "lost calls" in Teams, from the other phone i can't see any audio and the call go in error after few seconds

here some settings for my user that are the same as the other users

AllowPrivateCalling TRUE

AllowWebPSTNCalling TRUE

AllowSIPDevicesCalling FALSE

AllowVoicemail UserOverride

AllowCallGroup TRUE

AllowDelegation TRUE

AllowCallForwardingToUser TRUE

AllowCallForwardingtoPhone TRUE

PreventTollBypass FALSE

BusyOnBusyEnabledType ENABLED

PopoutForIncomingPSTNcalls DISABLED

SPAMFilteringEnableType ENABLED

AllowCallRedirect DISABLED

thanks

[#6]

@iCobretti 

Do you know if you're using media bypass?  What operating system? I'm assuming Windows? I see you mentioned that you're on the same network as others that do not have the same problem, so that should in theory eliminate a network firewall, what about firewall on the workstation? Can you disable it and retest?

There are different port requirements between the Windows client, and the browser client.  Teams should handle the firewall stuffs automatically, but it might still be an issue.