[AusNOG] Telstra DOT, VoIP HELP!

[TWIG Security]

Hi All,
     I am looking to upgrade a client from simple cordless phone 
(plugged directly into V7610 Modem on a DOT service ) to an mini IP-PBX 
as the cordless phone idea supplied by TBS is not cutting the mustard.  
Multi-building site with users in any one of 4 buildings.

I have been trying on and off for a week to get the SIP Server and any 
proxy from the Business help desk for a week, and all they will provide 
is the user/pass for the VoIP service, saying they don't have access to 
the SIP details.   I checked the modem and its a canned device (no 
access to anything other than User/Pass).

Has anyone worked on this previously and know where I can get the 
required info, SIP details, preferred Codecs etc.

Cheers,

Mal