E1/T1/J1 Trunk Overview

This topic describes what is E1/T1/J1 trunk and the differences among the three types of trunk. This topic also provides the information of E1/T1/J1 crossover cable.

What is E1/T1/J1 trunk

E1/T1/J1 is known as Primary Rate Interface (PRI), an Integrated Services Digital Network (ISDN) access method, which enables traditional phone lines to carry voice, data, and video traffic.

  • E1/T1/J1 trunk is only supported on Yeastar P560 and P570.
  • To extend E1/T1/J1 trunk, you need to install EX30 expansion board on the PBX. One EX30 expansion board provides an E1/T1/J1 port.

Differences between E1, T1, and J1

The PRI consists of B channels at 64 kbit/s each and D channel at 64 kbit/s each. The B channels are used for voice or user data, and the D channel is used for any combination of data, control/signalling, and X.25 packet networking.

According to the number of B-channels and D-channels, there are three types of PRI interface: E1, T1, and J1.

PRI Type Description

Contains 30 B-channel and one D-channel and is used in Europe, China, and most of the Asian countries.

T1 Contains 23 B-channel and one D-channel and is used in the USA, Canada, and Hong Kong.
J1 It is almost the same as T1 but used in Japan with some slight modifications, this is the Japanese standard for PRI.

E1/T1/J1 crossover cable

You can get an E1/T1/J1 crossover cable from the carrier or make a crossover cable yourself.

Note: E1/T1/J1 crossover cable is different from the Ethernet cable, but you can make a crossover cable by an Ethernet cable.
The pinouts of an E1/T1/J1 crossover cable is shown as the following figure.