Symptom

Call flow is the following: Ipphone--CUCM--SIP--CUBE--SIP/TLS--MSTeams RTP-----------------------CUBE-------------SRTP MS sends multiple 180 ringing messages and then a 183 ringing with SDP. This trigger media forking on the CUBE and the RTP does not get encrypted, the SRTP coming from Teams is passed down to the phone as is (without decrypting it before), the phone plays static as the payload is encrypted and the phone was not supposed to use SRTP.

Conditions

Microsoft teams send multiple 180 messages without SDP and then a final 183 with SDP.

Workaround

None

Further Problem Description