modem

Device for transmitting computer data over telephone lines. Such a device is used to convert digital signals produced by computers to analogue signals compatible with the telephone network, and back again.

Modems are used for linking remote terminals to central computers and enable computers to communicate with each other anywhere in the world. In 1997 the fastest standard modems transmitted data at a nominal rate of about 33,600 bps (bits per second), often abbreviated to 33.6K.

56K modems, launched in 1997, achieved higher speeds by using a digital connection to the user's computer, while using a conventional analogue connection in the other direction. ADSL modems can achieve data transmission rates of up to 24Mbit/s downstream and 3.5Mbit/s upstream rate by using digital communications to both the computer and also over the telephone network.