Network Interface - Sound Card Turning a sound card into a modem.

Ok, here's a challenge that I know is possible, but I need a little help. I think alot of people would be interested in using this, once they realize the possibilities.First, I would like a way of getting online for *free* without doing anything illegal. I also want to be able to do so wirelessly.Here's the solution that I came up with. I have a cell phone that is on a family-plan. All calls between me & anyone else that has my service provider is free. The phone I have doesn't have the option of using it as a modem, so I would like to use my soundcard as a modem, use the cell phone just as a way of carrying the modulated data. I've taken a cheap headset, removed the earbud/mic, and attached 2 stereo plugs. If I plug them into my soundcard, any sound played from my computer is sent through the phone to the other person. And anything they say can be recorded by my computer. So I realized that if my computer can send/recieve sound from the cell phone, it should be easy enough to do the same with data. I know that ages ago, instead of a modem that just directly connected to the phone line, you had a box that you would place the handset of your phone on. That box would convert your data to audio, and the phone would transfer it.I know that copying the old bbs & terminal software would probably be the easiest for transfering data, but I want to go a step further, and have it talk tcp/ip. Yes, I know that a cell phone connection would probably be slow. I'd probably be lucky to get a 2400 baud connection, but for simple stuff, it'd be all I need. Certainly all I'd need for e-mail.My problem is this, I don't know how to write drivers for windows. I could do all the code talking to the sound card, that's easy enough. I need to know how to tell windows(95) that I have a new type of network interface. I could also use some help getting the most effecient transfer rate.I know that this is a rather challenging problem, but I think if it can be solved, it'd make it so that alot of people could take more advantage of the free connections that cell companies offer.-YB