[asterisk-users] Problem with 2 machines connected with IAX

[Matt]

Hi,
I am purchasing minutes (800) from provider a (from now on A).   My
server is B, and my customer is C.  When an 800 call comes in it goes:

A--->sip-->B-->iax-->C and it sounds fine.

If the customer at location C puts the caller on hold (local phone
hold), when they pick the caller back up the caller can hear customer,
but the customer can not hear the caller.

If the customer at location C puts the caller on park (70), when they
pick the caller back up everyone can hear everyone.

Any thoughts?