Avaya 03-300430 User Manual

Combined with a TN767E circuit pack, Avaya’s 120A1 Integrated CSU module becomes an 
enhanced CSU. The 120A1 CSU, combined with new switch software and the functionality 
provided by a TN767E’s hardware and firmware, provides functionality equivalent to an external 
stand-alone Avaya ESF T1 CSU. The 120A1 CSU connects to the TN767E circuit pack on the I/
O connector panel on the back of the port carrier, and thus becomes an integrated part of the 
system. Throughout this document, the term 120A1 means a 120A1 (or later-suffixed) CSU.
The 120A1 CSU and the TN767E are for use in the United States of America with 1.544-Mbps 
DS1 service. For more information about the 120A1 CSU module see DEFINITY® 
Communications System Generic 1, Generic 2 and Generic 3 V1 and 2 – Integrated Channel 
Service Unit (CSU) Module Installation and Operation, 555-230-193.
A TN767E and a 120A1 integrated CSU support on-demand loop-back tests assisting fault 
detection between the:

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TN767E circuit pack and the integrated CSU

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Integrated CSU and an optional customer-premises loop-back jack

●

Integrated CSU and a remote CSU.

These loop-back tests are explained in detail later in this DS1-BD section, but 

on page 980 gives a high-level overview 

of the loop-back points.
The following list of acronym definitions are for 

●

PLB = Payload Loopback

●

BLB = Board Loopback

●

ELB = Equipment Loopback

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LLB = Line Loopback

●

RLB = Repeater Loopback

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CLJ = Loop-Back Jack Loopback

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R-LLB = Remote Line Loopback

●

SMRT = Smart Jack

●

LPBK = Loopback

For more information about DS1 interfaces, refer to the DEFINITY® Communications System 
Generic 2.2 and Generic 3 V2 DS1/CEPT1/ISDN-PRI Reference, 555-025-107.