VOIP I always encounter, “log in timed out.”

I am trying to log in to VoIP using the following information:
- Username: Your phone number, e. g. 086262xxxx – Note the 0.
- Authorization User: Your phone number – e. g. 086262xxxx – Note the 0.
- Password: VoIP Password.
- Domain / Realm: iihne.iinet.nt.au.
- SIP Proxy: sip.<state>.iinet.nt.au.
When I log in, I always encounter, “log in timed out. ” Upon checking my settings, I find a black where the outbound proxy should be and I’ve turned off the firewall. The administrators informed me that there is no trace of me logging in at all. I am using Windows XP SP2. Could there be something blocking my access?
Thanks.
