Types of Modems Depending upon how your computer is configured and your preferences, you can have an external, internal or PC modem card. All three types work the same way, but each has its advantages and disadvantages. This is the simplest type of modem to install because you don't have to open the computer.
External modems have their own power supply and connect with a cable to a computer's serial port.
The telephone line plugs into a socket on the rear panel of the modem. Because external modems have their own power supply, you can turn off the modem to break an online connection quickly without powering down the computer. Another advantage over an internal modem is that an external modem's separate power supply does not drain any power from the computer. You also can monitor your modem's connection activity by watching the status lights. Most internal modems come installed in the computer you buy.