A device that adds 3G or 4G (LTE) cellular connectivity to laptops, desktop computers and various tablets. Typically available as an external USB module, for desktop computers, the modem may also be available on a PCI or PCI Express (PCIe) card that plugs into an empty slot on the motherboard. For older laptops, modems may be available for ExpressCard or PC Card/CardBus slots.Known By Many NamesA cellular modem via USB is a "USB modem." On a card, it can be an "air card," "data card" or "broadband card." Generic terms are "broadband adapter," "broadband modem," "cellular adapter," "3G or 4G modem."Alternatives: Smartphones and RoutersWhile a cellular modem plugs directly into the computer, smartphones and stand-alone broadband routers convert cellular signals into a Wi-Fi hotspot to connect to nearby devices. See cellular hotspot and mobile broadband router.