scope:

In order to carry out maintenance in the public switched telephone network of switched 64-kbit/s digital circuits, digital circuits at sub-rates of 64 kbits/s, and N ∞ DS0 digital circuits (up to the maximum payload of a primary rate facility), a digital circuit test system is defined for digital exchanges and digital PBXs. Currently, only digital loopback testing is defined in this standard. Further study is required to develop other types of digital test lines (e.g., responder type testing).

Purpose

This standard specifies a loopback test line capable of being used in the measurement of error performance of switched digital circuits for purposes such as:

a) The analysis of reports by customers of degraded error performance.

b) A repair verification check of error performance prior to a return to service of circuits previously reported as faulty.

c) A pre-service check using enhanced test patterns to ensure proper implementation of DS0/DS1 equipment options that affect circuit operation.

d) A pre-service check of the proper provisioning of switches supporting N ∞ DS0 services. N ∞ DS0 channels require that bit sequence integrity be maintained. This may be incompatible with some types of switching equipment and so special routing must be provisioned for these calls.

e) A pre-service check to establish a performance benchmark.

f) An off peak hours Auto Routine Test for the purpose of maintaining network performance standards.