Is there anyway to connect to a pppoe (ROS) server without first having to connect to an ISP first (Be on the Internet)

I would like to give my customers Internet Access (Be their ISP) - All of them have got ADSL lines.

I.a.w their DSL username must be something like customer@mydomain.com and authenticate on my ROS pppoe server, and gain
internet access via my network.

Thanks