My CM is connected to the PSTN via a SIP trunk with IOS router. When a call comes from OffNet(PSTN), I can blind-transfer the call back to an OffNet destination with no problem. The original caller can hear MoH and ringing tones before the destination is off hook. But if I transfer the call to another internal(OnNet) destination, the caller hears MoH while the transferred number is typed and then is left blank. The transfer can succeed but the caller just does not get any signal that the transfer is continuing.
Any ideas to troubleshoot this is appreciated.