No MOH through IAX trunk

Hey,

I have a Queue function call some local SIP phones and then on no-answer try the Queue function to a bunch of IAX channels that are reached on another machine through an IAX trunk.

Music on Hold plays as expected for the SIP clients but when the IAX channel is rung, the line goes silent and no MOH or ringing is heard. Once the person answers the channel, voice can be heard clearly.

Any ideas? :unamused: