I have had trouble with rp3, Did you set it up and try debugging to see if ppp is starting?
It should tell you if it has a problem usually with chat scripts.
There is a great Howto out called Howto Hookup PPP in Linux that will definately work, it includes scripts and everything about troubleshooting from beginning to end.
Sorry but I don't have the link anymore.
If you can find it you will be all set.
Ok I found it here
http://axion.physics.ubc.ca/ppp-linux.html
Read the whole thing and save a copy.
Heck, save two copies.
No Bull this is the best I have ever seen.