Teams Calls not being Recieved by 3CX Despite Set-up followed?

[pjn1973]

This is for a TEST system for a PoC validition for a client, NOT the ikopbx....

I suspect that some of this 'might' be Teams related, however, after setting up the integration by the book for a client that I need to demonstrate the integration to, i can't get outbound calling functioning. Inbound calls work with no problems and are recieved by the Teams client, however, to my knowledge, even though I can see the SIP acknowledgements in 3CX to ping requests from Microsoft. As a result the SBC (3CX) is obviously valid and working - is there anything that might be obviously missing on the 3CX side before i et MS involved??

Call ID - d1f17351-e05d-5dc8-9faa-048c92baa9f0​

Nov 06, 2025 9:34:40 AM GMT |User: Peter Neal |Caller number: +44 1494 ****** |Call type: dr_out

No data found - possible reasons can include:

1. The call session is new and that data has not yet been uploaded to Teams Admin Centre.
2. The call session is older than 30 days and the data has been purged.

 

[pjn1973]

The error is 504: Unable to deliver INVITE: A connection attempt failed...

 

[KyriacosS_3CX]

Calling out from the PBX directly works?

 

[pjn1973]

Yep

 

[Charles_3CX]

You can open a ticket with 3cx technical support so that we can request the required data to investigate why this is happening.

 

[pjn1973]

Thanks Charles, i'll keep looking on it as I'm loathe to buy support for a Proof of Concept for a client particularly if they end up going elsewhere.