Contents

Introduction

Problem

Solution

Introduction

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.

Problem

The IP phone sends Real-Time Transport Protocol (RTP) packets to the wrong IP address after it resumes a transferred or on-hold call.

Solution

Complete these steps in order to solve the problem:

1. On the gateway, configure a loopback interface and the h323-gateway voip bind srcaddr ip_address command, 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.

2. Globally configure voice rtp send-recv on the gateway.

This command is documented in Cisco IOS Voice, Video, and Fax Commands: Si through Z.

3. Verify that you have selected correct MOH codecs in the service parameters for Cisco IP Voice Media Streaming Applications.