i want to use radius server to record authentications on Cisco routers?

users will call a toll-free number through PSTN lines to my Cisco routers where i want to record authentications on Cisco routers to bill. I think to use MySql, Apache, PHP on Linux platform. Ur technical advises on implementation are appreciate in advance. I have database/programming experience on Microsoft but new on open-source platform. But willingly to cope as the new challenge.