Modem Eliminator is a device for connecting two pieces of data terminal equipment (DTE) without modems by providing timing signals and handshaking for synchronous transmission.
How it works
Modem eliminators provide an easy way to connect two pieces of DTE without a modem. They simulate a synchronous transmission data link by generating a clocking signal. Modem eliminators provide speeds of up to 2.048 Mbps and use RS-232, RS-422/485, RS-530, V.25, or X.21 cabling.

Modem eliminators are similar to line drivers, but modem eliminators simply connect two pieces of DTE, while line drivers connect DTE to data communications equipment (DCE). Also, line drivers regenerate signals and thus extend the maximum possible distance, while modem eliminators do not. Finally, line drivers are used in pairs (one at each end of the line), and modem eliminators are used singly and are placed at the midpoint between the two devices being connected.