I am facing an issue. whenever we are tryimg to call from location A to location B, the phone rings just once and then dropped. After performimg some R&D, we found that the issue is happening with only one phone model type, all other phone model type working fine. So please tell me what could be the issue and how can we troubleshoot it.
What is the Call Manager and the affected Phone model version? Is the phone registered as SIP or SCCP? Need to isolate if this is a signalling problem or media negotiation is at stake.
Can you disable the 'G722 advertise' on either sides (phones) through the CM Admin - phone configuration page and test? Also, what is the codec settings between the 2 sites?
Collecting CCM traces would isolate if it is a signalling or media negotiation issue.
Hope this helps.
Cisco IP phone-8941 connected to the same network as other ip phones ? in another way, did the effected ip phone device have the same subnet IPs as other IP-phone devices ?