Sorry about that, try this:
BT requires that you enter your BT username and password and these settings:
Encapsulation - PPP over ATM (PPPoA)
Multiplexing Method - VC-Based
Virtual Circuit - VPI=0 - VCI=38
Modulation - Multi mode
Authentication - CHAP
Failing that, I would call BT and ask them for proper settings
Here are their Numbers, call Free Phone Number first.
0800 1690199
0845 6007020
0870 2404650
Regards,
Alex.