Multi-Tech Systems MVP-2400, MVP-2410, MVP-3010 manual Isdn Interfaces ST and U, 540

Cable Pinouts MultiVOIP User Guide

ISDN Interfaces: “ST” and “U”

The MVP410ST and MVP810ST are ISDN-BRI voip units that use an S/T outlet interface. You will need an NT1 device to connect these units to any network equipment that has the “U” ISDN interface. In the UK, and in many European countries, the telco supplies an NT1 device for ISDN-BRI service.

An ISDN Basic Rate (BRI) U-Loop consists of two conductors from the telco central office to the customer premises. The equipment on both sides of the U- loop accommodates the extensive length of the U-loop and the noisy environment in which it may operate. At the customer premises, the U-loop is terminated by an NT1 (network termination 1 ) device. An NT1 device makes an end-user’s 4-wire terminal equipment compatible with the telco’s 2-wire twisted pair ISDN-BRI line.

The NT1 drives an S/T bus. The S/T bus is usually made up of 4 wires, but in some cases may be 6 or 8 wires.

“S” and “T” refer to connection points in the ISDN specification.

When a PBX is present, S refers to the connection between the PBX and the terminal. (“Terminal” can mean any sort of end-user ISDN device: data terminals, telephones, FAX machines, voip units, etc.)

Point T refers to the connection between the NT1 device and customer supplied equipment. Terminals can connect directly to the NT1 device at point T, or there may be a PBX (private branch exchange, i.e., a customer-owned telephone exchange). The figure below shows “S” and “T” connection points in an ISDN network.

Point “S”

4-8 Wires

Point “T” NT2 4-8 Wires (PBX)

Telco

Central

Office

Terminal

NT1

Point “U” 2 Wires

Point “S”

Point “S”

Terminal Terminal

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