[Asterisk-Users] SIP, NAT and Asterisk

[* KAPIL *]

Greetings!

I am using a Linksys PAP2 (SIP) adapter and trying to connect to an Asterisk
server located behind a router doing NAT. 

UDP ports 5060-5061 and 10000-20000 are forwarded to the internal IP address
of the Asterisk server. I even tried putting the server in the DMZ but the
results were the same.

When I have the Linksys adapter INSIDE my LAN...everything is fine. When I
try to connect to Asterisk from outside the LAN, one of two things
happens...either the adapter can't register with the SIP server or the
adapter does connect but I get one-way audio or no audio at all during phone
calls.

I have been able to google some information about how SIP is notoriously bad
with NAT and firewalls....but there doesn't seem to be an easy fix.

Any ideas?