dialup that backbones off broadband connection
 

I was wondering, since I have a spare machine, and that I go to other people's houses sometimes and need the Internet, if I could just put a modem in my one Linux machine, and just have it that, I call my home phone with a computer with a modem from someone else's house, and I just login via the telephone line, to the broadband on the LAN.

So basically, to simplify, I wish to install a modem in my Gentoo Linux computer, in which I can dialin from somewhere else, then, the modem in the server would forward all the data coming into the modem into eth0, onto the LAN, then through my Cable Internet, then back.

Now my question is, does the server HAVE to have a voice modem, so that the modem can tell weither it's a voice or data call? Because if it's a voice call, I just want it to not answer, and let it go to our home answering machine. If it's data, I want it obviously answered and giving Internet.

Finally, will the fact that the server phone line has call waiting, ruin the connection? And also, can the calls just be forwarded to a software answering machine or something?