This is from a working config used to call out to net2phone using their SIP server
The only trick is they restrict access to specific user agents, so you must falsify Asterisks user agent string.


I tested with above configuration and it works perfectly..............Nahid

Edit by RazaMetaL:
I've tested it with:
useragent=Cisco ATA 186 v3.1.0 atasip (040211A)

And works very well :)