As depicted by its name, an external modem device located outside the CPU. External modem connected to the CPU via COM or USB port. This type of modem typically uses a separate voltage source adapter. The advantage of this type of modem usage is good enough portability so easily removable for use on other computers. Besides, by using an external modem, there should be no expansion slot that sacrificed so that could be used for other purposes, especially if the mainboard is used only to provide some expansion slot. External modem is also equipped with an indicator light that allows us to monitor the status of the modem. The disadvantage, are more expensive than internal modems. External modem also requires a separate place to put it a little though.

Unlike the external modem, internal modem is connected directly in the CPU. Physically, the form of an internal modem card plugged into one of the expansion slot on the mainboard, usually on the ISA or PCI slot. The use of this type of modem has several advantages, among others, are more efficient in terms of place and more economical prices compared to the external modem. Because they have been installed on the CPU, the modem does not require this type of adapter as an external modem that seem more compact system with no moving around a lot of wires that could give the impression less tidy. However, the internal modem has a weakness as the absence of indicators that can be found on the external modem. The result was difficult to monitor the status of the modem (though it can be done via software). In addition, the internal modem does not use their own voltage source to be fed from the power supply to the CPU. Heat from the components in a series of internal modems will also increase the the CPU. Heat from the components in a series of internal modems will also increase the temperature of the CPU box.