VoIP Phones - FireBrick
Here is a quick overview of configuring the FireBrick to register with AAISP, and then setting up the configuration for a phone to then register against the FireBrick to be able to make and receive calls.
Create the General VoIP config:
Create a Carrier:
<carrier name="AAISP" display-name="Office" allow="22.214.171.124-119 2001:8b0::/48" registrar="voiceless.aa.net.uk" username="0123456789" password="secret" extn="100" max-calls="2" comment="Office 0123456789"/>
Create a User
On your phone, you'd set up the account using the credentials set here - ie the username and password.
This is only a short overview of getting a single phone working with a single carrier - there is much more the FireBrick can do with it's built in PBX features. See FireBrick SIP Configuration for more details.