Every sip address I try and point my phone to doesn't seem to work.  When I call my number, I get 'the number you have called is not in service"

I am wanting to divert my vfx phone (when not answered) to my gizmo5 account, as this runs on my mobile

the sip-uri I entered was XXXXXXXX@proxy01.sipphone.com.

A friend of mine is on 2talk, I tried to divert to his 2talk account (xxxxx@2talk.co.nz), but that didn't work either..

I could divert to another vfx user using username@xport.co.nz though.....

Am I doing something wrong, or does sip-uri not work for 'outside vfx' ?