Thanks mate! Specifying the extension same as the username and then using extension-in-contact fixed the problem. It now registers successfully with the switch.

 

I do though still get the message:

2010-01-29 01:30:05.634220 [NOTICE] sofia_reg.c:2267 Added gateway 'Test-Inbound' to profile 'external'

2010-01-29 01:30:05.634547 [ERR] sofia.c:1663 ERROR: username param is REQUIRED!

2010-01-29 01:30:05.634657 [ERR] sofia.c:1663 ERROR: username param is REQUIRED!