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:

<voip comment="AAISP">

Create a Carrier:

<carrier name="AAISP" display-name="Office" allow="81.187.30.110-119 2001:8b0::/48" registrar="voiceless.aa.net.uk" username="0123456789" password="secret" extn="100" max-calls="2" comment="Office 0123456789"/>

Create a User

Here we restrict access to this account by our LAN IP range - in this case 90.155.42.0/27 - change this to your LAN block.

On your phone, you'd set up the account using the credentials set here - ie the username and password.

<telephone name="myPhone" display-name="Arnold" username="arnold" password="secret" allow="90.155.42.0/27" ddi="+44123456789" extn="100" carrier="AAISP" max-calls="1"/>

Going Further

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.