That's a scam alright. That is why I NEVER trust internal modems. I don't even have a phoneline modem anymore, just a cable modem connected to a PCI ethernet card.
There was a thread here a while back that I cannot find with a search now. Someone had received a phone bill with a huge charge to what was basically a 900 number that they never dialed. There is an article at Reuters, that I can't find here is a link to the Yahoo story good luck:
Basically there was a company that was sending out those dialer programs that re-dialed your computer into the internet through a 900 number in madagascar! The company that handled the billing is in trouble now and all the money is going into an escrow account until they decide if it should be refunded.
So whoever that was here with the problem, if this is the same company that scammed him he may get his money back