Pre-recorded MAC address type of service

Hi all:

I'm new in this list.

My customer is wanting to  bypass browsing based authentication.. so 
mobile devices can just jump on the service just as easily.

I've been researching this and it seems that most WISP providers do use 
the usual authentication method.

I would like to know if someone would point me in the right direction here.

I want to know what code to modify so we allow pre-registration of IP 
Phone's MAC addresses..  so the gateway does allow those MAC addresses 
through, just as transparently as possible.

I have pre-viewed a commercial product's web site that would do exactly 
that, but I want to exhaust all my options with Open Source NoCat


Any information greatly appreciated.

Thank you.
Carlos
NZ