Proxy ADSL users

[Ashraf Al-Basti]

Dear All,
is there any way to limit the access for ADSL user to be from a specific 
ATM port? I have an ATM DSLM and want to proxy the request to a specific 
ISP, depending on some attribute, and need a help to do know the 
attributes which i can use to do that? i did that for the dial up users 
using Called-Station-Id, but for the ATM DSLM i didnt know what can i 
use to do the same?