A modem that attaches to the computer externally, usually through a serial port, and has its own power supply. An external modem operates no differently than an internal modem, although it can be shut off without turning off the entire computer.
modem that is plugged into one of the serial ports on a computer. External modems often have lights on them showing current activity. Because they are external, they also have to have their own power source and power switch. Due to the case, power supply, and cable that an external modem requires, the price is usually more than an internal modem, though only by about $20. External modems do not have UART chips built into them.