Nortel Meridian

[1] Exploratory development on digital technology, common for the SL-1 (PBX) and the DMS (public switch) product lines, began in 1969 at Northern Telecom, while R&D activities related to the SL-1 started in 1971.

In the early 1970s, most PBXs were either electromechanical (e.g. cross-bar) or based on a hybrid technology (e.g. switching matrix made from a two-dimensional array of contacts but control performed by an electronic logic).

[2][3][4] Its success went on to power the company into a leadership position in the telephony world, and led to expanded designs "up and down" to provide products at all sizes, including the DMS series high-end machines, and the Meridian Norstar for smaller installations up to 200 users.

[5] The Meridian was one of the few PBXs still available from a major communications supplier that can be configured as non-VOIP PBX and could be upgraded to a hybrid system with VoIP added.

It provides 16 voice and 16 data communication links between a Meridian 1 switch and modular digital telephones.

Digital line cards are housed in the Intelligent Peripheral Equipment (IPE) Modules.

The circuit interface operates by a transformer coupling which provides foreign voltage protection between the TCM loop and the digital line.