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 |
|---|---|
| E1 |
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.
