One major benefit is the diagnostic lights that appear on the modem's front panel. These lights have abbreviated letters near them that stand for particular communication actions. These lights let you know current communication status and help you to diagnose any problems with the modem, phone line or computer. You can connect an external modem to any computer with a serial port. For example, you can use the same modem for your laptop that you use with your desktop in the office.
Internal modems plug into an available slot inside the computer.
These modems aren't as portable as an external device because certain computers are restrictive in the amount of available slots, the size of the case or the lack of available power. Since these internal modems aren't equipped with their own power supply, they must use the computer's central power supply. Internal modems don't feature diagnostic lights like an external modem but they have less cabling to mess with. These credit-card sized modems offer most of the same features, speed and capabilities of the internal and external modems. ISDN phone lines handle voice and data more effectively than standard telephone lines.