This is a non technical forum. Actually, Herve's Bar & Grill was called "All thoughts non-technical" before.
You catch my drift???
Then again I have to admit that I can't really help you...but it seems like kppp either sends no or a wrong modem init-string. Modems have - kinda like printers - a more or less standardized vocabulary with which they can be controlled. For example there are commands to initialize the modem for a new connection, to dial, to drop the connection etc. etc.
Most of these commands - if not all - start with "at". IIRC at-z is the standard "do something you lazy modem"-command. Could you provide more info on what kppp says or does it just say "busy"?