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Calls are dropped when transferred in Cisco CallManager version 3.1 due to a codec mismatch between the MOH server and the IP MOH region


Core Issue

In Cisco CallManager 3.1 versions, upon transfer, the codecs for the Music On Hold (MOH) region and those supported by the server need to match. If they do not, the call is dropped. Calls to IP phones through a gateway fail when a transfer to another phone is attempted. This issue also applies to putting calls on hold and establishing conferences. Refer to Cisco bug ID CSCdv05335 for the latest details on causes, workarounds, and fixes. For more information on configuring MOH, refer to Music On Hold.


Go to Service > Service Parameters > Cisco IP Voice Media Streaming App. The DefaultMoHCodec parameter determines which codec is used when streaming MOH. To implement a workaround, select all that are required for your network. Update, stop and restart the IPVMSApps service.

To change the codecs used in the MOH server, perform these steps:

  1. In the Cisco CallManager, select Services > Service Parameters.
  2. Select Server > Cisco IP Voice Media Streaming App.
  3. Select Supported MOH Codecs*, hold the Crtl key and click on all the codecs listed.
  4. Click Update at the top of the page.
  5. Select Application > Cisco Call Manager Servicability > Tools > Control Center > (choose server).
  6. Stop, then start the Cisco IP Voice Media Streaming App.

Note: This may interrupt some services.

Alternatively, upgrade to Cisco CallManager 3.2 or later.

Problem Type

Call control software  (CallManager, CallManager Express, ICS7750, SRST, SS7 call agents)

Call connection  (Connection quality: One-way audio, no busy tone, dropped calls, etc.)

Call Control


Call Connection

Dropped or disconnected calls

CallManager Features

Music on hold (MoH)

When Problem Occurs

During transfer

While on hold

Bug ID Number


Codec Type

Codec mismatch

Default codec

CallManager Services

Cisco IP voice media streaming app

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