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Services

Interface Characteristics T1

T1 is a differential communications interface using two pairs (TX and RX) connected through a single RJ-48C connector (also frequently written as RJ48, RJ-48 or RJ48c and also often incorrectly called RJ-45 or RJ45 – it is an RJ connector with 8 contacts assigned according to specification RJ-48C). To enable reliable transmission and reception over 1000s of metres of cable between customer premises and telephone exchanges, the data is encoded using B8ZS to produce a bipolar signal with the required characteristics. Note that timing information (i.e. the bit clock) is encoded within the signal to enable the receiver to recover a clock and correctly decode the received data.

Interface Applications

Telecommunications companies (in the relevant territories) provide and support E1 or T1 services to end-users (usually business customers) in a variety of channel configurations with associated price structures. The organisation of data carried using E1 or T1 services is defined within the G.704 standard.

E1 and T1 lines are used for a VERY wide variety of uses including Voice, Internet Access, X.25, Multiplexed data, ISDN. Both E1 and T1 lines are frequently connected to X.21 or V.35 connections by network interface converters before connection to the communications equipment.