We have an IVR system (Frontrange) that is connected via SIP Trunk to the Call-manager. We route one of our main numbers via SIP to this IVR. When an External Caller calls a Cisco phone and the phone initiates a transfer to this main number, while completing the transfer an error displays on the phone stating "External Transfer not available" and "cannot initiate transfer". I tried calling internally from a cisco phone to another cisco phone and initiating transfer, works fine. Tried calling from an external number (i.e. in-state & out-of-state number) to a cisco phone and inititating transfer, works intermittently for in-state but doesn't work when calling from out-of-state. Couldn't find anything in the logs. Had a case open with TAC and they couldn't find anything odd in signalling. Did anyone encounter this kind of an issue. Any thoughts or suggestions on this.
