For a while around a quarter century ago PC motherboards came with a special slot, a little shorter than the PCI slots which ruled the roost back then, and offset from them further into the case.
These modems would often slot into a Mini PCI-e slot in the netbook motherboard ... a Mini PCI-e to USB adapter used to add a 12-axis sensor to a laptop.
A device that adds wireless connectivity to a laptop or desktop computer ... USB modules as well as PCI or PCI Express (PCIe) cards that plug into an empty slot on the motherboard.