Configuring BT SIP Trunks

Hi everyone,

Is there anyone who successfully configured British Telecom SIP trunks? If yes, can you please share your sip trunk settings?




I was able to solve my problems following the instructions provided on the link below. The only difference I used the proxy server name provided by BT instead of the suggested That’s what I put in the /etc/hosts file.

Hopefully this will be of some use to those wanting to use their Asterisk setup with Broadband Talk - assuming you have the right BT Broadband option, this means various free calling options and billing on your normal telephone bill. Quality also seems good.

  1. Confirming BBT Details
    Go to … umerConfig
    Enter your Broadband Talk phone number (without any leading 44’s) and the password in your Welcome email.
    On the following screen, click Configure Router/Hub. Another window will pop up. Right click on the Configure button and choose ‘Copy Link Location’ (Firefox) or similar in your browser. Paste this into a text file.

This will contain one long line of SIP configuration items, but crucially it includes your actual SIP password for Broadband Talk.

Look for the entry &SIPPassword1= and copy all the following characters until the next & sign. Mine is 18 characters.

Save this information somewhere safe!

  1. Setting up your hosts file
    The BT SIP server does not have a domain entry, and relies on use of a proxy. To make this work, it’s necessary for your Asterisk system to think it’s talking to rather than the proxy (

To do this, edit your /etc/hosts file, and add a line:

(there is a tab after the end of the IP address)

The IP address should be obtained by doing an ‘nslookup’ or similar on Only add one address.

  1. SIP.conf - Register String
    The format for the register string is:

The number must be stated in the format 44xxxxxxxxxx. The BBT Password is the long one identified in Stage 1.

  1. SIP.conf - Definition
    [email protected]
    secret=<long password from Stage 1>

Other things to watch:
BT have different expiry settings for SIP registrations. I had to play around to find settings that worked, but eventually went for:

Note that all of the above assumes you have a working Asterisk installation, no NAT issues, etc, I found it best to verify everything with a more straightforward service like VoipUser before getting into this.

Hope this helps somebody!