Wideband switching supports end-to-end connectivity between customer endpoints at data rates from 128 to 1536 kbps over T1 facilities and to 1984 kbps over E1 facilities. Switching capabilities support wideband calls comprised of multiple DS0s that are switched end-to-end as a single entity.

Wideband switching is designed for ISDN application equipment such as ISDN video codecs, but can also interface to non-ISDN application equipment by using PRI terminal adapters. In the same sense that a data module acts as a DCP or BRI terminal adapter between endpoint data, such as V.35 and dialing interfaces such as RS-366 and a DCP interface, a PRI terminal adapter acts as a wideband terminal adapter between endpoint data and dialing interfaces and a line-side ISDN-PRI interface. Wideband switching introduces PRI endpoints on line-side interfaces.

A PRI endpoint has a unique extension number and consists of one or more contiguous B-Channels on a line-side T1 or E1 ISDN-PRI facility. Endpoints initiate and receive calls via ISDN SETUP messages indicating the data rate and specific B-Channels to be used, and communicate all other call status information via standard ISDN messages. Any ISDN signaling set such as Avaya, CCITT, or ECMA may be used for a line-side ISDN-PRI facility.

Multiple PRI endpoints on one line-side facility are separate and distinct within the facility. Non-overlapping contiguous sets of B-Channels are associated with each PRI endpoint, and the endpoint equipment is expected to initiate calls within these boundaries. The endpoint application equipment must: