External versus internal

The external modem is a self contained unit (box) which you can use with any computer. It has a cord which runs to the computer’s serial data port (also called as communications port) and another cord which runs to telephone jack. The modem will probably have a jack into which you can plug to your phone set.

An internal modem can be printed-circuit board, also called as card, which is commonly installed in new computers. Virtually all the desktop computers come having modems. A new notebook computer may not have an internal modem installed; in that case you can purchase one in the form of a PC card that fits into a slot on the side of the computer. This card is roughly the height and width of the credit card, but somewhat thicker.