Asterisk 1.4.0 to asterisk 1.2.? connection

I have 2 asterisk servers connected via a vpn connection. I setup up a iax2 account on both servers. Now when I call from one asterisk server to the other, the extensions answering are getting a static connection. The voice comes through fine for a little while and then starts to break up. What settings do I need to modify to get better sound quality?

Here is my iax.conf settings:

[gphone]
username=gphone
type=user
context=default
secret=???

Here is my extensions conf:

[jcksnasterisk1]
exten=>_23.,1,Dial(IAX2/gphone:gphone@192.168.3.2/${EXTEN})
exten=>_23.,2,Congestion()
exten=>_23.,102,Busy()

Thanks

Eric

this could be from your vpn not having enough bandwidth or something… try it with sip accounts just for shits, does that help?