These modems would often slot into a Mini PCI-e slot in the netbook motherboard. [delokaver] figured out how to use these 3G cards over USB instead. It’s actually a fairly straightforward hack.

Typically available as an external USB module, for desktop computers, the modem may also be available on a PCI or PCI ... or PC Card/CardBus slots. A cellular modem via USB is a "USB modem." ...