[Asterisk-Users] Need Advice

[izo]

Unless you gave g729 licence for asterisk i'd suggest to go with some 4 port
gateway with g723 protocol at both ends. 
IMHO you would benefit more from G723, VAD and jitterbuffer on those
gateways then from plain iax trunking.

If you want to go SIP you might have to use other port then 5060 which
is somethimes block.

I used successfully h323 on quintum's with g723 over vtund tunnel to
US to gnugk and then to providers

regards
m.