[Asterisk-Users] Asterisk NAT Gateway Setup

[Kevin]

I am currently using Asterisk behind Belkin NAT router.  With what ever
NAT router I have used, I have had difficulties in registration and
audio problems with my SIP provider (Iconnect and Nikotel)

It was suggested that I try to connect the asterisk box directly to the
internet avoiding the NAT transition.  As I will still need internet
connectivity, I am trying to make the asterisk box the NAT gateway.

I have an additional NIC for my Asterisk box.  

As I am no Linux or Asterisk expert, can anyone make suggestions as to
this approach and any recommended steps to accomplish this?

Also, how would Asterisk know which interface to bind to?  I know there
is a bindaddress= parameter in the SIP config, but the address to the
internet is dynamic via DHCP from my cable provider.

Thanks,

Kevin