Calls from a phone registered to a CME to a phone registered to a Unified CM complete. If the CM phone then transfers the call to another CM registered phone, the latter called phone hears no audio, and the call eventually drops. External calls from the PSTN can be transfered, only calls originating from CME phones have the calls dropped after a transfer. Have not found a problem with any other calls between the CM phones and CME phones. Any suggestions?