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IP to IP calls - sendErrorToMX Cause Code 47


7942 Firmware SCCP42.9-1-1SR1S

I am having random instances of Disconnect Cause Code 47 dissallowing calls from being answered. I usually look towards Codec/MTP for this type of cause, but I am getting these on Cisco IP to IP calls.  In this cluster I have one device pool and one default region so I *should* not be doing any transcoding.

I will attach a snippet of a trace that includes things like:

|AgenaInterface(604812)::sendErrorToMX, Phone return error for SMT

|MediaManager(584974)::wait_AuConnectErrorInd, mCleanupPreallocatedMTP=0

Any help is appreciated,


  • IP Telephony
New Member

IP to IP calls - sendErrorToMX Cause Code 47

I am having  a similar issue. What was the issue in your case ?


IP to IP calls - sendErrorToMX Cause Code 47

In this case I believe we disabled G.722 in the service parameters, prevented it from being advertised in the enterprise parameters, and reset the devices.  I think we were seeing a lot of that cause code when going to ATA 187's but if memory serves correct did see it from phone to phone as well.

Hope that helps.

New Member

IP to IP calls - sendErrorToMX Cause Code 47

Thanks for your help. This solution worked. I found the following root cause supporting your recommendation.

Note Starting with Unified CM 5.1, G.722 is used as the default codec  for regions that are configured for G.711 on devices that support G.722.  However, G.722 is not supported with silent monitoring and call  recording based on CAD, CTI OS, or Unified CM. To disable this default,  in Unified CM Administration go to Enterprise Parameters and set  Advertise G.722 Codec to disabled.