Multi-Tech Systems MVP210-SS User Manual download pdf (Page 384)

Cable Pinouts MultiVOIP User Guide

384

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.

Te lc o

Central

Office

Point “S”

Point “T”

4-8 Wires

Point “S”

4-8 Wires

Point “U”

2 Wires

Point “S”

NT1

NT2

(PBX)

Te r min al

Terminal

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Multi-Tech Systems MVP210-SS User Manual Page 384