A modem is an essential piece of communication technology when connecting digital equipment over analogue telephone lines. Modem is short for Modulator – Demodulator and they work of a standard communication protocol for connecting modems to computers called RS232. Modems also have a standard command protocol called the Hayes command set.
Almost all computers have standard RS232 serial ports as either old style 9 pin D connectors or more likely on modern equipment as a USB adapter. A USB to D connector cable is used to connect the computer with the modem. In some laptops, the modem may be integrated into the device as an internal modem.
In the earlier days of the internet during the 90’s, dial-up access using 56Kbps modems was the standard method of access to a local ISP using the standard telephone line. Nowadays cable and DSL have made many modems obsolete but they are still valuable devices in rural areas where internet or even telephone lines are not the norm. In that case 3G mobile network modems can be used that can transmit and receive data at much higher data rates facilitating high-speed internet access.
Mobile broadband modems are used in many remote applications simply by installing a SIM card for a local mobile services provider. A further evolution uses 3.5G HSPDA, which provides data download speeds over many megabits per second. Often service providers supply these dongles as part of a data package and they are superficially locked to their own network using preconfigured AP settings. However, these can usually be easily reset to work on any providers Network and SIM.
Smartphones and some tablets have modems built into them that support the Hayes modem command set and therefore can be used as a broadband mobile router by connecting the device to the computer’s USB port.