I need some help on this issue.
We have a SIP trunk for Incoming & Outgoing calls connected on 3845 Router (IOS 12.4). The SIP gateway & CCM 6.0 has a H323 trunk and we are using Unity 5.0.
The problem here is when someone calls the Main number it goes to Auto Attendant. If some dial the extension number the call is transferred but there is no ring back tone sent to the caller. The IP phone rings and if no answer it goes to the Voicemail and the caller hears the greeting.
Incoming calls to DID are working fine with ringback tone heard by the caller.
I think it could be a codec issue. Not sure.