[asterisk-users] NAT solutions

[Gordon Henderson]

On Wed, 24 Jan 2007, Yuan LIU wrote:

> I have a really dumb question.  It appears that Yahoo, MSN, AIM, you name 
> them, they don't have a NAT problem, and some use SIP.  I don't think they 
> all stay in voice path, either.  What takes?

Their SIP servers aren't behind NAT firewalls, so the problem shifts from 
them to you ...

In the UK, there is a good number (100's of thousands? More?) of ADSL 
customers who also connect their PC directly to the 'net (via free USB 
adapters that most ISPs supply) so in this situation you could well be 
using a soft-phone on one PC to talk to another soft-phone on another PC, 
both directly connected to the net without NAT, using a non NATted SIP 
server of some kind to setup the call, then data doesn't need to be 
hairpinned via the SIP server.

And they are possibly using proprietary clients that know more about 
NATting than a generic SIP client might, so can use this to avoid NATting 
issues too...

Gordon