If you have a problem with your modem and call your MLS vendor for technical support, the support engineer will need to know what kind of modem you have. Generally, you don't have to worry about the protocol your modem uses, unless you buy a high-speed modem. That's because modem speeds tend to increase every few years as a result of technological breakthroughs. The newest, fastest, and most expensive modems tend to use proprietary protocols, so they often don't work with modems from other manufacturers. As a result, modems can almost always talk to each other at less than the fastest speed currently possible.
Modems can either be internal or external .