I'm in Marin this week living in a hotel where the only Internet access, described cheerfully by the woman at the front desk turned out to be "a data-port in the side of your room's phone."
After a few hours hacking away with incorrect information given to me by the Cingular rep (who chuckled when I said I was using a Macintosh) I finally figured out how to connect at a whopping 56kbps. I even made a phone call while connected!
Anyway, this guy's mobile phone modem scripts saved me from going insane. Everything you need to know is on his site.