ISDN fallback adapter

Definition of ISDN fallback adapter in The Network Encyclopedia.

What is ISDN Fallback Adapter?

A device that allows you to back up digital data service (DDS) lines using a dial-up Integrated Services Digital Network (ISDN) line.

If the DDS line experiences failure, the fallback adapter automatically kicks in the ISDN line to maintain wide area network (WAN) connectivity.

Fallback adapters typically have built-in ISDN terminal adapter functionality and can sometimes provide backup support for multiple DDS lines.

The fallback and restore settings are configurable using a built-in or serial-connected terminal interface.

To use a fallback adapter, you connect it to the ISDN line with the RJ-45 connector and to the local area network (LAN) bridge or router and the DDS CSU/DSUs (Channel Service Unit/Data Service Units) using the V.35 or RS-232 serial interfaces.

Graphic I-15. ISDN fallback adapter.