DS1 span testing with a loopback jack

Last Updated : Jan 09, 2024 |
The DS1 Customer Premises Equipment (CPE) loopback jack is a hardware device that loops the CPE’s transmitted DS1 signal back to the CPE’s receive DS1 signal to test and isolate potential wiring faults in the DS1 span between the system and the network interface point. The loopback jack is used with the following DS1 interfaces:

  • MM710

  • G430 Branch Gateway, G450 Branch Gateway

The DS1 line can be either private or through a DS1 service provider. The interface to the DS1 line can be either a direct interface to a repeatered line or through a Smart Jack that is typically provided at the network interface. The loopback jack works in configurations that use

  • no Channel Service Unit (CSU)

  • an external CSU

  • a CSU module between the DS1 interface and the interface to the DS1 line

    Note:

    The loopback jack operates with the 120A ICSU only; not the 31xx series of Channel Service Units (CSUs), other external CSUs, or earlier ICSUs.