A self-contained modem that is connected to the serial or USB port of a computer. The older serial port models draw power from a wall outlet and have the advantage of status lights on the outside of the case that show the changing states of the modem (off-hook, carrier detect, transmitting, etc.). The term may also refer to broadband modems for cable and DSL use. Contrast with internal modem. See USB modem, cable modem and DSL modem.