DCNS offers a Recharge Modem Service, which offers its subscribers the ability to purchase dedicated high speed premium modem service to the campus network. The service is a single hunt group composed of the number of subscribers' modems plus two spares attached to Annex terminal servers. Subscribers can purchase one or more modems and authorize access to those modems to others. We've had very good success in interacting with alot of different brands of modems. If you are conservative, you should probably opt for the US Robotics modems.
Prices are dropping, so check around.
You might try the people who sold you the modem, but failing that, Workstation Services is very experienced in helping people with Macintosh, PC and Unix workstations problems. They should be able to help you if you run into any problems hooking up your modem and configuring it and your computer. It's available on gopher. Subscriptions are free to universities, colleges, departments, faculty, staff and students.