There is a modem in each unit with hispeed cable for your computer, so basicly a wideband where you do not need dialup. I seem to remember it also has WIFI antenna covering the whole unit when you have WIFI capability on your computer. (AirTran now has WIFI in cabin for your free use during flight.)
A dial up must be by phone line, bring a phone line extension with you and insert in phone plug-in just in case.
I uset to do that many years ago. It's slow!
Other owners with more knowledge in that field?

Carl
Thanks for the information.