Also called an IMUX, a device that can perform inverse multiplexing of digital telecommunication channels. A typical IMUX might be capable of inverse multiplexing together four Basic Rate Interface ISDN (BRI-ISDN) lines, two T1 lines, or four T1 lines to provide a throughput of 512 Kbps or 5.888 Mbps, respectively.
This saves the expense of having to purchase or lease equipment to individually terminate each Integrated Services Digital Network (ISDN) or T1 line, and it provides an efficient way to increase wide area network (WAN) speed for high-bandwidth uses such as videoconferencing, T1 backup, or large file transfers.
IMUXes can include built-in CSU/DSU (Channel Service Unit/Data Service Unit) functionality, they have a 34-pin built-in V.35 LAN (data) interface, and they have an RJ-45 or DB25 connector for the line interface.
They often feature load-sharing functions so that if one ISDN or T1 line goes down, no delays occur. IMUXes usually include diagnostic and loopback functions for both local and remote troubleshooting.