Hello,
We are experiencing an issue with Cisco SIP Phones 78xx and 88xx when making calls through CUCM with SNR (Single NumbCUCM and Phone 7800, Unified Communicationser Reach) enabled.
Issue description:
- When calling a mobile phone that is not connected to the network, the operator message ("This number is not reachable") is played in parallel with the ringing tone on the Cisco phone.
- This issue only occurs on 78xx/88xx series SIP phones. Other models (79xx, softphones, Webex) do not have this behavior.
- We suspect an issue related to Early Media (183 Session Progress with SDP).
What we have tried:
- Checking SIP signaling logs: CUCM seems to accept 183 from the provider, but only 78xx/88xx play the audio.
Questions:
- Is there a way to disable Early Media specifically for 78xx/88xx?
- Any known bug or firmware issue on these models?
Any help would be appreciated!
CUCM Version: 14.0.1.13900-155
Firmware version of 78xx/88xx: sip78xx.14-3-1-0101-131
