VoIP Phones - Zyxel VMG Router
Go to the Menu --> VoIP --> SIP option.
Then the SIP Service Provider tab.
Click on the edit symbol next to the "ChangeMe" entries and fill in the details below. Note that you are required to fill in a "SIP Proxy Server Address" but this is not the same as "Outbound proxy server" which can be found hidden under the drop down advanced section. AAISP DO NOT NEED OUTBOUND PROXY SET!