Core Issue
There are several reasons for Cisco CallManager to play Tone on Hold (ToH) to an endpoint that has been configured for Music on Hold (MoH):
- One reason is a mismatch between the codec configuration used by the MoH server and the region in which the endpoint is registered. For example, the MoH server advertised only a capability of G.711 mu-law. If an endpoint is in another region enforcing the G.729 codec, the Cisco CallManager chooses ToH because a stream cannot be played to this endpoint.
- If location-based connection admission control is being used and there is no bandwidth available, then Cisco CallManager sends ToH rather than MoH.
- If there are no available audio streams, it is because the MoH server has a finite number of unicast streams it can generate. Exceeding this limit causes Cisco CallManager to play ToH.
Resolution
To resolve this issue, ensure that each of these issues are not causing ToH to be played.
For more information on resolving this issue and other MoH problems, refer to the following documents:
For step by step configuration of MoH refer to Music On Hold topic of the Cisco CallManager Features and Services Guide
For FAQ on MoH refer to CallManager Music on Hold Frequently Asked Questions
Also refer to Chapter 12: Music on Hold from the Cisco Press book Troubleshooting Cisco IP Telephony [ISBN: 1-58705-075-7] for detailed troubleshooting steps of MoH and various other issues.
