IP Communicator will not make calls over a SIP trunk

[dickc]

I am running CCM 5.1.3.4000 and Ip Communicator 2.1.4.0. I have an SIP trunk setup on the call manager g711u.

I have a few laptops loaded with IP Communicator, some work, others do not. They will all call within the network. The problem shows itself when they try to call out the SIP trunk. The ones that don't work get a ring and when the other end picks up they get a fast busy.

[Nicholas Matthews]

You have a codec mismatching problem. Either add a transcoder for the VPN'd phones, or you have an MTP on the SIP trunk that you need to support the g729 or g711 codec on.

[dickc]

How do you add support for codecs on the MTP?

This happens even when the laptops are local so I wouldn't think a transcoder will help.

[dickc]

a