This document describes the scenario in which a user gets one way audio issue with Cisco CallManager after a call is transferred or placed on hold, if the H.323 endpoint that is configured on the CallManager is a Fast Ethernet subinterface of the gateway. This occurs especially when the Music on Hold (MOH) is enabled.
The IP phone sends Real-Time Transport Protocol (RTP) packets to the wrong IP address after it resumes a transferred or on-hold call.
Complete these steps in order to solve the problem:
On the gateway, configure a loopback interface and the h323-gateway voip bind srcaddr ip_addresscommand, as described in H.323 Support for Virtual Interfaces. Ensure that you use this loopback IP address when you configure the Cisco IOS H.323 gateway.