I have a CUCM 8.5 and a CUBE out to a provider. Everything works except if a call is forwarded to either and internal or external number then the caller doesn't hear ringback. If you wait and the call is answered then it proceedes correctly. I can get it to work by forcing MTP to be used but then the calls to the provider only advertise one codec which they don't like.
Just wondered if there is a way ruond this without using MTP...could it be a codec thing and the MTP is being used as a transcoder??
I have a working configuration template that supports supplementary services and ringback on transfer without the need for an MTP. Do you want to email me off list?
Dana, are you please able to post or email your config for this? We are experiencing the same issue on our CUCM 8.5 after migrating to SIP.