Forum Discussion

Copper Contributor

Feb 26, 2020

REASON Q.850;cause 18 text Call Controller timed out while waiting for acknowledgement.

Incoming calls to Microsoft teams get disconnected automatically after 20 seconds. You can make a call from outside, teams phone rings, answer the call, 2 way communication is there but still teams c...

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Devaraj Narayanappa

Copper Contributor

Mar 10, 2020

Eerik Kiskonen Our issue is finally fixed.

The solution was SBC was sending the IP address in ACK messages for 200 OK it received from Teams. Teams expect contact header FQDN from the 200 OK in the ACK message, not the IP.

nicolastanski

Copper Contributor

Apr 19, 2020

Devaraj NarayanappaCould you share with us what is the correct way to send the Contact header in inbound calls?

I am trying like this but occur the same error.

Contact: <sip:CALLERID_NUMBER@SBC_FQDN:5061;transport=tls>

Thanks.