SIP Service Provider - InPhonex
InPhonex offers a free SIP phone number service for PC to PC calls as well as providing real number for residents of the USA, Canada, and the United Kingdom. They make their money selling that gateway service as well as hardware (e.g., SIP routers).
Sign Up Here: www.inphonex.com/reg/newuser.php
SIP Configuration Settings:
||[Your Inphonex Number]|
||[Your Inphonex Password]|
|SIP Proxy Server: