[Asterisk-Users] X-lIte behind NAT and Asterisk behind NAT

[richard]

Hi,
I have the following scenario.
I have an Asterisk server running on an internal IP address behind a 
firewall, and I have a remote user trying to connect to my Asterisk box 
behind his firewall, but he can't seem to get a connection.
I have opened up the port (5060) so that he can connect through my 
firewall, but it still doesn't appear to want to connect.
I am pretty sure that the firewall rules are correct, because I have 
also open up port 21, and he can successfully ssh into my Asterisk box.

Any ideas/pointers?

Thanks in advance

Richard