---[  Phrack Magazine   Volume 8, Issue 52 January 26, 1998, article 11 of 20


-------------------------[  The Subscriber Loop Carrier (slick)


--------[  Voyager[TNO]



=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


 I............................................... Overview
 II.............................................. The Central Office Terminal
 III............................................. The Remote Terminal
 IV.............................................. SLC-2000 Shelves
 V............................................... Where might you find an RT?
 VI.............................................. SLC Interface Software
 VII............................................. SLC Glossary
 VIII............................................ SLC Vendors



+----------+
| Overview |
+----------+


A Subscriber Loop Carrier (SLC) (often pronounced "slick") is a
multiplexer which allows a large number of analog lines to be provided
over a very small number of digital lines.  A good example is the AT&T
SLC 5, which allows 192 subscriber loops to be provided through two or
four digital lines. SLCs are also referred to as Digital Loop Carriers
(DLCs).

The first SLC was installed in 1971.  As of 1995, between 5 and 10% of
all lines are served by SLCs, as are roughly 50% of all new lines built
each year.  SLCs are available from quite a few vendors.  This article
focuses on the extremely popular SLC-2000 from AT&T.

A SLC usually consists of two separate subsystems, the Central Office
Terminal (COT) and the Remote Terminal (RT).  The COT is connected to
the RT via a DS1 circuit.  The DS1 circuit may be carried over actual T1
lines, or it may be carried over another medium such as lightwave or
digital radio.  The RT is then connected to the subscribers using a
Voice Frequency (VF) circuit.  The VF circuit is what you and I would
recognize as our normal phone line.

This diagram illustrates a subscriber loop constructed using an SLC:

 +---------+                                                      
 |         |                                               /---------\
 | Central |                     +----+                   /-----------\
 | Office  |                     |    |        
 |         | --- DS1 circuit --- | RT | --- VF circuit -- | Residence |
 |  (COT)  |                     |    |                   |           |
 |         |                     +----+                   +-----------+
 +---------+



+-----------------------------+
| The Central Office Terminal |
+-----------------------------+

The SLC-2000 COT is a modular design usually consisting of the following
components:

        . Access Resource Manager (ARM) shelf
        . Metallic Distribution Assembly (MDS) shelves
        . Heat Baffles
        . Alarm and Test Unit (ATU)


 +--------------------------+
 |  |  |  |  |  |  |  |  |  |  <------- Alarm and Test Unit
 |--------------------------|
 | |                        |  <------- Heat baffle
 |--------------------------|
 ||||||||||||||||||||||||||||
 |:::::::::::::::::::;::;:::|  <--\
 |--------------------------|      \___ Access Resource Manager (ARM) shelf
 |:;;;;;;::;::::::::|||||||||      /
 |.##||||.|,,,,,,,,,........|  <--/
 |.##||||' '''''''''|||||||||
 |--------------------------|
 | |                        |  <------- Heat baffle
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 | |                        |  <------- Heat baffle
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 +--------------------------+


+---------------------+
| The Remote Terminal |
+---------------------+

The SLC-2000 RT is a modular design usually consisting of the following
components:

        . Access Resource Manager (ARM) shelf
        . Metallic Distribution Assembly (MDS) shelves
        . High Density Fiber Optics Shelf (HDOS) shelves (FITL only)
        . Cooling fans



An SLC-2000 RT configured for a Metallic Application
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 +--------------------------+
 | |                        |  <------- Fan unit
 |--------------------------|
 ||||||||||||||||||||||||||||
 |:::::::::::::::::::;::;:::|  <--\
 |--------------------------|      \___ Access Resource Manager (ARM) shelf
 |:;;;;;;::;::::::::|||||||||      /
 |.##||||.|,,,,,,,,,........|  <--/
 |.##||||' '''''''''|||||||||
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 |--------------------------|
 |!!!!!!!!!!^^||^^!!!!!!!!!!|  <------- Metallic Distribution Shelf (MDS)
 |!!!!!!!!!!^^||^^!!!!!!!!!!|
 +--------------------------+


An SLC-2000 RT configured for a Fiber In The Loop (FITL) Application
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 +--------------------------+
 | |                        |  <------- Fan unit
 |--------------------------|
 ||^||^||^||^||^||^||^||^||^|  <------- High Density Optics Shelf (HDOS) #2
 ||^||^||^||^||^||^||^||^||^|
 |--------------------------|
 ||^||^||^||^||^||^||^||^||^|  <------- High Density Optics Shelf (HDOS) #1
 ||^||^||^||^||^||^||^||^||^|
 |--------------------------|
 | |                        |  <------- Fan unit
 |--------------------------|
 ||||||||||||||||||||||||||||
 |:::::::::::::::::::;::;:::|  <--\
 |--------------------------|      \___ Access Resource Manager (ARM) shelf
 |:;;;;;;::;::::::::|||||||||      /
 |.##||||.|,,,,,,,,,........|  <--/
 |.##||||' '''''''''|||||||||
 |--------------------------|
 | | | |     ||||| | | | |  | <-------- Metallic Distribution Shelf (MDS) #4
 | | | |     ||||| | | | |  |
 |--------------------------|
 | | | |     ||||| | | | |  | <-------- Metallic Distribution Shelf (MDS) #3
 | | | |     ||||| | | | |  |
 |--------------------------|
 | | | |     ||||| | | | |  | <-------- Metallic Distribution Shelf (MDS) #2
 | | | |     ||||| | | | |  |
 |--------------------------|
 | | | |     ||||| | | | |  | <-------- Metallic Distribution Shelf (MDS) #1
 | | | |     ||||| | | | |  |
 +--------------------------+



+------------------+
| SLC-2000 Shelves |
+------------------+

The SLC-2000 is divided into a number of shelves, each of which hold
circuit cards that are responsible for specific functions within the
SLC.  Some shelves are found only in COTs, others are found only in
RTs, while most shelves are used in both COTs and RTs.


Access Resource Manager (ARM) Shelf
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ARM shelf provides feeder interface, bandwidth management and
circuit maintenance features.

The ARM shelf consists of the following functional component groups:

        . User Interface Panel (UIP)
        . Integrated Test Head (ITH)
        . Provisioning Display Controller (PDC)
        . Bandwidth Management Complex
        . DS1 distribution
        . DS1/VT feeder interfaces
        . SONET feeder


The following diagram illustrates the functional components of an ARM shelf:


        /<-- ESD ground jack
        |/<-- Power Converter Unit
        || /<-- Transmission Signaling Unit
        || |   /<-- Analog Measurement Unit
        || |   | /<-- Power Amplifier Unit
        || |   | | /<-- Craft Access Unit
        || |   | | | /<-- System Memory Unit
        || |   | | | | /<-- Provisioning and Display Controller
        || |   | | | | |   /<-- Link to Alarm and Networks
        || |   | | | | |   | /<-- DS1 interfaces
        || |   | | | | |   | |
       +----------------------------------------------------+
       |^                                                   |
       |----------------------------------------------------|
       ||P|T| |A|P|C|S|P| |L|D|D|D|D|D|D|D|D|.|.|.|.|.|.|.|.|
       ||C|S| |M|A|A|M|D| |A|S|S|S|S|S|S|S|S|---------------|
       ||U|U| |U|U|U|U|C| |N|1|1|1|1|1|1|1|1| | | | | | | | |
       ||.|.|.|.|.| |.|.|.|.|.|.|.|.|.|.|.|.| | | | | | | | |
       |------------------------------------+ | | | | | | | |
       || | | | | | | | | | | | | | | | | | | | | | | | | | | <-\
   /-> || | | | | | | | | | | | | | | | | | | | | | | | | | |   |
  |    ||.|:|:|:|:|:|:|.|.|:|.|.|.|.|.|.|.|.|:|:|:|:|:|:|:|:|   |
  |    ||.|.|.|.|.|.|.|.|.|.|.|.|.|.|.|.|.|.| | | | | | | | |   |-\
/-|    |------------------------------------+ | | | | | | | |   | |
| |    || |o|o| | | | | ||| | | | | | | | | |---------------|   | |
| |    ||.|o|o| | | | | |:|:|:|:|:|:|:|:|:|:|.|.|.|.|.|.|.|.|   | |
|  \-> ||.| | | | | | | | |:|:|:|:|:|:|:|:|:| | | | | | | | | >-/ |
|      ||.| | | | | | | | | | | | | | | | | | | | | | | | | |     |
|      +-----------------------------------------------------     |
|          | | | | | | | | |                                      |
|          \ / \ \ / / | | \-- Test Head Controller (THC)         |
|           |    \ /   | \-- System Controller (SYSCTL)           |
|           |     |    \-- Overhead Controller (OHCTL)            |
|           |     \-- STS-1 Multiplexer (MXRVO)                   |
|           \--- Optical Line Interface Unit (OLIU)               |
\-- Synchronous Timing Generator (TGS)                            |
                                   Bandwidth Management Complex --/




The User Interface Panel (UIP) represents the highest level of
interaction possible with the SLC-2000 without plugging some other
piece of equipment into it.  Here is a close-up of the User Interface
Panel:

                                                           Abnormal -->\
   AMD (Alphanumeric Message Display) -->\          NE Activity >--\   |
                        Attention -->\   |           Major -->\    |   |
                  Panel Fault -->\   |   |     Critical -->\  |    |   |
   /<-- ESD ground jack          |   |   |                 |  |    |   |
   |                             |   |   |                 |  |    |   |
 +------------------------------------------------------------------------+
 |   | ~=~ ~~~  ~~   ~~ ~~~~~~ | __  ____________________  __ __   __  __ |
 | O |________/----------------| |/  |* User Int. Panel |  |/ |/   |/  |/ |
 |   |                         | __  ~~~~~~~~~~~~~~~~~~~~  __ __   __  __ |
 |   | = = ooo ####  ## :::::: | |/  ^v  #  #  #  o#  #    |/ |/   |/  |/ |
 +------------------------------------------------------------------------+
       ||| |||   |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
       ||| \|/   |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
       \|/  |    |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
        |   |    |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
Fuses-->/   |    |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
Power test  |    |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
  points -->/    |   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
CIT connector -->/   |  ||||||   |   |   |  |  |   |  |    |  |    |   |
  DDS clock conn. -->/  ||||||   |   |   |  |  |   |  |    |  |    |   |
DDS Maintenance Jack -->/|||||   |   |   |  |  |   |  |    |  |    |   |
 DS0 Maintenance Jack -->/||||   |   |   |  |  |   |  |    |  |    |   |
  DS1 Maintenance Jack -->/|||   |   |   |  |  |   |  |    |  |    |   |
   T-R Maintenance Jack -->/||   |   |   |  |  |   |  |    |  |    |   |
  T1-R1 Maintenance Jack -->/|   |   |   |  |  |   |  |    |  |    |   |
    E&M Maintenance Jack -->/    |   |   |  |  |   |  |    |  |    |   |
                        Power -->/   |   |  |  |   |  |    |  |    |   |
                    Scroll Buttons ->/   |  |  |   |  |    |  |    |   |
                                Enter -->/  |  |   |  |    |  |    |   |
                                  Escape -->/  |   |  |    |  |    |   |
                                   LED Test -->/   |  |    |  |    |   |
                                            ACO -->/  |    |  |    |   |
                                            Update -->/    |  |    |   |
                                                  Minor -->/  |    |   |
                                                Power Minor ->/    |   |
                                                    FE Activity -->/   |
                                                            Session -->/




There are many connections on the UIP.  The Electrostatic Discharge
(ESD) ground jack is for a static control wrist strap.  The Craft
Interface Terminal (CIT) connector is a DB-25 for plugging in a CIT or a
PC running terminal emulation software.  The DDS clock connector
provides a clock source for test sets.  The Power Test Points allow you
to monitor the -48v power to the unit.

There are many LED's on the UIP.  The Attention LED is yellow when the
there is something new on the Alphanumeric Message Display (AMD).  The
Panel Fault LED is red when the UIP is in need of repair.  The Power LED
is green when -48v power is present.  The Power Minor LED is yellow when
the system is operating on battery power. The Alarm Cut Off (ACO) LED is
green when the ACO button has been pressed during an alarm.  The
Critical LED is red when a failure has caused a loss of service for 128
or more customers.  The Major LED is red when a failure has caused a
loss of service for 24 or more customers.  The Minor LED is yellow when
an error exists, but is not causing a loss of service to any customers.
The Near End (NE) Activity LED is yellow when the local terminal has
some alarm condition.  The Far End (FE) Activity LED is yellow when the
remote terminal has some alarm condition.  The Abnormal LED is yellow
when the SLC-2000 is not in a mode that provides service, such as a test
mode. The Session LED is yellow when a technician has a CIT connected to
the remote terminal.

The most interesting part of the UIP is the Alphanumeric Message Display
(AMD) and the buttons associated with its use.  The AMD displays a
single 24 character line of text.  The scroll buttons may be pushed to
move forward and backward through various menu choices.  The <Enter> and
<Escape> keys work just as you might imagine.

Three types of messages appear on the User Interface Panel (UIP):

        . Automatic Messages
        . Fault Messages
        . Alarm Messages


        Automatic Messages are triggered by pressing certain buttons,
        UIP or PDC unavailability, and SYSCTL installation.

        Fault Messages are displayed when the RETRIEVE-FAULTS command is
        selected on the UIP.

        Alarm Messages are displayed when the RETRIEVE-ALARMS command is
        selected on the UIP.


The Automatic Messages are:

        . PANEL FAULT
        . MN:NE:pdc unavail
        . UPDATE: In-Progress
        . UPDATE: done
        . SONET SUBSYS UPDATE done
        . SYSCTL INITIALIZATION
        . SYSCTL EXTENDED INITZN
        . SYSCTL EXTND INITZN done
        . STATUS -LOCAL SONET
        . STATUS -LOCAL SONET SITE
        . STATUS -REMOTE SITE 1
        . STATUS -REMOTE SITE 2
        . STATUS -REMOTE SITE 3
        . STATUS -REMOTE SITE 4
        . STATUS -REMOTE SITE 5
        . STATUS -REMOTE SITE 6
        . STATUS -REMOTE SITE 7
        . STATUS -REMOTE SITE 8


        "PANEL FAULT" indicates that the User Interface Panel (UIP) has
        failed and is unable to communicate with the Provisioning
        Display Controller (PDC).

        "MN:NE:pdc unavail" indicates that the Provisioning Display
        Controller (PDC) is unable to communicate with the User
        Interface Panel (UIP) because it has failed, or because software
        installation on the PDC is in progress.

        "UPDATE: In-Progress" indicates that the UPDATE button has been
        pressed and that an update is in progress.  (See "Update button"
        below.)

        "UPDATE: done" indicates that an Update has been completed in
        response to the use of the UPDATE button.

        "SONET SUBSYS UPDATE done" indicates that an Update has been
        completed in the SONET subsystem in response to the use of the
        UPD/INIT button on the SYSCTL.

        "SYSCTL INITIALIZATION" appears for 10 seconds after a SYSCTL
        with working software has been inserted.  If the UPD/INIT button
        on the SYSCTL is pressed while this message is displayed, the
        SYSCTL will reset all SONET parameters to their factory
        defaults.

        "SYSCTL EXTENDED INITZN" appears after SYSCTL INITIALIZATION has
        been completed.

        "SYSCTL EXTND INITZN done" appears after SYSCTL EXTND INITZN has
        been completed.

        "STATUS -LOCAL SONET" indicates the User Interface Panel (UIP)
        indicators reflect the alarm status of the local system only.
        The letter "L" is displayed in the SYSCTL 7-segment display.
        This occurs when the user toggles the Far-End Select (FE SEL)
        button on the SYSCTL.

        "STATUS -LOCAL SONET SITE" indicates the User Interface Panel
        (UIP) indicators reflect the combined alarm status of all the
        SONET network elements at the local site.  The SITE ID and a '.'
        is displayed in the SYSCTL 7-segment display.  This occurs when
        the user toggles the Far-End Select (FE SEL) button on the
        SYSCTL.

        "STATUS -REMOTE SITE x" indicates the User Interface Panel (UIP)
        indicators reflect the alarm status of REMOTE SITE x.  The
        number "x" is displayed in the SYSCTL 7-segment display.  This
        occurs when the user toggles the Far-End Select (FE SEL) button
        on the SYSCTL.



There are several other miscellaneous buttons on the UIP.  The LED Test
button lights up all of the LED's to allow quick identification of burnt
out LED's. The Alarm Cut Off (ACO) button shuts off the current alarm
condition. The Update button operates much like the "Detect New
Hardware" icon in Windows95, except that on the SLC-2000 it never locks
up your system.




Metallic Distribution Shelf (MDS)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The MDS provides control and distribution for Data Service 0 (DS0) and
Fiber In The Loop (FITL) interfaces.

The following diagram roughly illustrates an MDS shelf assembly in a
metallic configuration:

 +-----------------------------------------------------------------------+
 |* AT&T  ##== ##== ##== ##==   ##== ##==    Metallic Distribution Shelf |
 |-----------------------------------------------------------------------|
 |~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|
 | :| :| :| :| :| :| :| :| :| *| *| *| *| *| *| :| :| :| :| :| :| :| :| :|
 | :| :| :| :| :| :| :| :| :| *| *|  |  | *| *| :| :| :| :| :| :| :| :| :|
 |=:|=:|=:|=:|=:|=:|=:|=:|=:|  |  |  |  |  |  |=:|=:|=:|=:|=:|=:|=:|=:|=:|
 |=:|=:|=:|=:|=:|=:|=:|=:|=:| *|  |  |  |  | *|=:|=:|=:|=:|=:|=:|=:|=:|=:|
 | || || || || || || || || || || || || || || || || || || || || || || || ||
 |!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||
 |-----------------------------------------------------------------------|
 |~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|~~|
 | :| :| :| :| :| :| :| :| :| *| *| *| *| *| *| :| :| :| :| :| :| :| :| :|
 | :| :| :| :| :| :| :| :| :| *| *|  |  | *| *| :| :| :| :| :| :| :| :| :|
 |=:|=:|=:|=:|=:|=:|=:|=:|=:|  |  |  |  |  |  |=:|=:|=:|=:|=:|=:|=:|=:|=:|
 |=:|=:|=:|=:|=:|=:|=:|=:|=:| *|  |  |  |  | *|=:|=:|=:|=:|=:|=:|=:|=:|=:|
 | || || || || || || || || || || || || || || || || || || || || || || || ||
 |!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||!||
 +-----------------------------------------------------------------------+


MDS upper and lower shelves are numbered from bottom to top.  On the
left and right side of each shelf half are 12 channel units (only 9 are
pictured in the ASCII diagram).  In the middle of each shelf half are
the common units.

The following diagram roughly illustrates an MDS shelf assembly in a
Fiber In The Loop (FITL) configuration:

 +-----------------------------------------------------------------------+
 |* AT&T  ##== ##== ##== ##==   ##== ##==    Metallic Distribution Shelf |
 |-----------------------------------------------------------------------|
 |AT&T|AT&T|AT&T|AT&T|      |~~|~~|~~|~~|~~|~~|AT&T|AT&T|AT&T|AT&T|      |
 |*   |*   |*   |*   |      | *| *| *| *| *| *|*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      | *| *|  |  | *| *|*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      |  |  |  |  |  |  |*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      | *|  |  |  |  | *|*   |*   |*   |*   |      |
 | || | || | || | || |      | || || || || || || || | || | || | || |      |
 | || | || | || | || |      |!||!||!||!||!||!|| || | || | || | || |      |
 |-----------------------------------------------------------------------|
 |AT&T|AT&T|AT&T|AT&T|      |~~|~~|~~|~~|~~|~~|AT&T|AT&T|AT&T|AT&T|      |
 |*   |*   |*   |*   |      | *| *| *| *| *| *|*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      | *| *|  |  | *| *|*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      |  |  |  |  |  |  |*   |*   |*   |*   |      |
 |*   |*   |*   |*   |      | *|  |  |  |  | *|*   |*   |*   |*   |      |
 | || | || | || | || |      | || || || || || || || | || | || | || |      |
 | || | || | || | || |      |!||!||!||!||!||!|| || | || | || | || |      |
 +-----------------------------------------------------------------------+


High Density Fiber Optics Shelf (HDOS)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The HDOS interfaces between the electrical signals on the MDSs and
optical signals on the Multi-Services Distant Terminals (MSDTs).

The following diagram roughly illustrates an HDOS assembly:

 +-------------------------------------------------------------------+
 |~~|~~|~~|~~|AT&T|~~|~~|~~|~~|AT&T|~~|~~|~~|~~|AT&T|~~|~~|~~|~~|AT&T|
 |~~|~~|~~|~~|    |~~|~~|~~|~~|    |~~|~~|~~|~~|    |~~|~~|~~|~~|    |
 |  |  |  |  |   .|  |  |  |  |   .|  |  |  |  |   .|  |  |  |  |   .|
 |  |  |  |  |    |  |  |  |  |    |  |  |  |  |    |  |  |  |  |    |
 |  |  |  |  |    |  |  |  |  |    |  |  |  |  |    |  |  |  |  |    |
 |OU|OU|OU|OU|    |OU|OU|OU|OU|    |OU|OU|OU|OU|    |OU|OU|OU|OU|    |
 | || || || ||   || || || || ||   || || || || ||   || || || || ||   ||
 | || || || ||PCU|| || || || ||PCU|| || || || ||PCU|| || || || ||PCU||
 |-------------------------------------------------------------------+
 | ~  ~  ~  ~  ~    ~  ~  ~  ~  ~    ~  ~  ~  ~  ~    ~  ~  ~  ~  ~  |
 |-------------------------------------------------------------------+
 |1 AMP FUSES -------> == == == == == == == ==                       |
 +-------------------------------------------------------------------+

Note: An HDOS contains 8 Optical Unit (OU) / Power Conversion Unit (PCU)
packs, not 4 as shown in the ASCII diagram.



Alarm and Test Unit (ATU)
~~~~~~~~~~~~~~~~~~~~~~~~~
The ATU panel reports alarms and trouble indicators using audible
alarms, visual indicators, and telemetry. In addition, the ATU provides
interfaces to the Pair Gain Test Controller (PGTC) and DC bypass pair
connections.

An ATU panel looks roughly like this:

 +---------------------------------------------------------------------+
 |      |      |      |      |      |      |      |      |      | *  * |
 |      |      |      |      |      |      |      |      |      | *  * |
 |      |      |      |      |      |      |      |      |      | *  * |
 +---------------------------------------------------------------------+

Here is a close-up of the indicator lights on the far right end of the
ATU:

                         +--------------+
                         |   __    __   |
             Fault --->  |   |/    |/   |  <-- Critical
                         |              |
                         |   __    __   |
              Busy --->  |   |/    |/   |  <-- Major
                         |              |
                         |   __    __   |
       Power Minor --->  |   |/    |/   |  <- Minor
                         |              |
                         +--------------+



Fan Units and Heat Baffles
~~~~~~~~~~~~~~~~~~~~~~~~~~
Fan units are used in RTs to provide cooling, while COTs use heat
baffles for the same purpose.

The fan unit looks in an RT looks something like this:

 +-----------------------------------------------------------------------+
 |*AT&T .| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 | ~*  ~~| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 |~~ o ~~| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 |  o  ~~| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 |~ o  ~~| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 |      .| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
 |~o     |  =============                                                |
 +-----------------------------------------------------------------------+


A close-up of the far left end of the fan unit looks like this:

 +------------------------+
 | *AT&T          o       |
 |         +----------+   |
 | FAULT * | CHANGE   |   |
 |         | FAN      |   |
 |+--------+ SPEED    |   |
 ||LED    O  (10 MIN. |   |
 ||TEST       TIMEOUT)|   |
 |+-------------------+   |
 |           10 -  - 212  |
 |      + O   8 -  - 176  |
 |            6 -  - 140  |
 | TEMP       4 -  - 104  |
 |            2 -  -  68  |
 |      - O   0 -  -  32  |
 |              V  F      |
 |             C=10 * V   |
 |  ESD            o      |
 |  ORD  O                |
 +------------------------+




+-----------------------------+
| Where might you find an RT? |
+-----------------------------+


RTs are found in quite an interesting variety of enclosures, including
metal and cast concrete.  Some are only large enough to hold the RT,
while others are environmentally controlled and large enough to hold the
equipment and several working technicians.


        . 44A + 44B Cabinets
        . WP-91071 Cabinet
        . 51A cabinet
        . 80D Cabinet (Community Service Vault)
        . 80E Cabinet (Community Service Vault)
        . Mini hut
        . Maxi hut
        . Concrete hut
        . Controlled Environment Vault (CEV)


The 44A Cabinet is a wall mounted cabinet that requires a 44B Cabinet 
to house the powering equipment.

WP-91071 Cabinet is a stand alone cabinet.

The 51A cabinet is 48" high by 29" wide by 20.5" deep.  The 51A cabinet
consists of three sections: the front door, the electronics section,
and the battery section.  The front door is hinged on the left and
opens to reveal the electronics section.  The electronics section is 
also hinged on the left, and opens to reveal the battery section.

The 80D Cabinet (Community Service Vault).

The 80E Cabinet (Community Service Vault).

The Mini hut is a prefabricated 6' by 10' by 8' high enclosure.

The Maxi hut, also known as the Electronic Equipment Enclosure (EEE) is
a prefabricated 10' by 20' by 8' high environmentally controlled
enclosure.

The Concrete Hut is 13' 2" by 7' 7 and 8' 8.5" high.  The walls of the 
Concrete Hut are made of precast concrete and are 4" thick.  The inside 
of the Concrete Hut is ventilated, heated and air conditioned.  The 
Concrete Hut is protected by intrusion alarms, smoke alarms, and high
temperature alarms.  

The Controlled Environment Vault (CEV) is a precast concrete enclosure
designed for installation below ground.  The CEV is cast in three parts:
the bottom half, the top half, and the entrance hatch.  The entrance to
a CEV shows a ladder leading down into the enclosure. The CEV is the
ultimate in environmental control.  In addition to ventilation, heating
and optional air conditioning, the CEV also features a gas monitor that
senses explosive and toxic gasses, a dehumidifier, and a sump pump.  The
CEV is lit by four fluorescent lamps backed up by an emergency lamp. The
CEV is protected by a gas alarm, a high temperature alarm, a
high-humidity alarm, a power-loss alarm, a high-water alarm and an
intrusion alarm.




+--------------------------------------------------------------+
| Enclosure        | Systems | Dual Channel Banks | Lines      | 
|------------------+---------+--------------------+------------+
| 44A+44B Cabinets |      2  |           1        |  192       |
| WP-91071 Cabinet |      4  |           2        |  394       |
| 51A Cabinet      |      2  |           1        |  192       |
| 80D Cabinet      |      4  |           2        |  384       |
| 80E Cabinet      |      8  |           4        |  768       |
| Concrete Hut     |  32(36) |       16(18)       | 3072(3456) |
| CEV (16')        |  40(44) |       20(22)       | 3840(4224) |
| CEV (24')        |  60(78) |       30(39)       | 5760(7488) |
| EEE              |  72(78) |       36(29)       | 6912(7488) |
+--------------------------------------------------------------+

Note: Number in parenthesis are applicable only to systems using bulk power.





+------------------------+
| SLC Interface Software |
+------------------------+


+--------------+
| SLC Glossary |
+--------------+


A&M     Addition and Maintenance
ACO     Alarm Cut Off
ACU     Alarm Control Unit
ACXT    Apparatus Case Crosstalk
ADPCM   Adaptive Differential Pulse Code Modulation
ADU     Alarm Display Unit
AIU     Alarm Interface Unit
ALBO    Automatic Line Build Out
ALC     Automatic Loss Compensation
ALIT    Automatic Line Insulation Test
AMD     Alphanumeric Message Display
ANI     Automatic Number Identification
ASN     Abstract Syntax Notation
ASU     Alarm Suppressor Unit
ATU     Alarm and Test Unit
AWC     Average Worst Case
B-E     Both-Ends
B8ZS    Bipolar with 8 Zero Substitution
BCU     Bank Controller Unit
BFU     Bank Fuse Unit
BIU     Backplane Interface Unit, Bank Interface Unit
BMP     Bandwidth Management Processor
CAU     Craft Access Unit, Channel Access Unit
CCITT   International Telephone and Telegraph Consultative Committee
CCS     Hundred Call Seconds
CDO     Community Dial Office
CDS     Circuit Design System
CENTREX Central Office Exchange Service
CEV     Controlled Environment Vault
CFU     Channel Fuse Unit
CIMAP   Circuit Installation and Maintenance Package
CIR     Customer Information Release
CIT     Craft Interface Terminal
CIU     Craft Interface Unit
CLC     Common Language Coordinator
CLEI    Common Language Equipment Identification
CLF     Carrier Line Failure
CLLI    Common Language Location Identification
CLRC    Circuit Layout Record Card
CMC     Construction Management Center
CMIS    Common Management Information System
CND     Calling Number Delivery
CO      Central Office
COACH   Customized On-line Aid for Customer Help
CODEC   Coder/Decoder
COE     Central Office Engineer
COT     Central Office Terminal
CP      Circuit Pack
CPC     Circuit Provisioning Center
CPI     Circuit Party Identification
CRC     Cyclic Redundancy Check, Circuit Redundancy Code
CSA     Carrier Serving Area
CSC     Community Service Cabinet
CSDC    Circuit Switched Digital Capability
CSPEC   Common Systems Planning and Engineering Center
CSS     Controlled Slip Second
CTB     Cut Through Board
CTU     Channel Test Unit
CU      Channel Unit
CUE     Channel Unit Emulator
CV      Coding Violation
CWG     Construction Work Group
CZ      Carrier Zone
DA      Distribution Area
DACS    Digital Access Cross-connect System
DCC     Data Communications Channel
DCLU    Digital Carrier Line Unit
DCU     Digital Connectivity Units
DDF     Digital Digroup Formatter
DDS     Digital Data Service
DF      Distributing Frame
DFI     Digital Facilities Interface
DID     Direct Inward Dial
DILEP   Digital Line Engineering Program
DLC     Digital Loop Carrier
DLI     Data Link Interface
DLP     Detailed Level Procedure
DLR     Design Layout Record
DLS     Digital Line Schematic
DLU     Data Link Unit
DM      Degraded Minute
DPO     Dial Pulse Originating
DPT     Dial Pulse Terminating
DPX     DATAPATH Extension
DR      Demand Repeater
DS0     Digital Signal 0, Data Service 0
DS0DP   Digital Signal 0 Dataport
DS1     Digital Signal 1 (1.544 MB/s)
DSDC    Distribution Services Design Center
DSL     Digital Subscriber Line
DSNE    Directory Services Network Element
DSPC    Distribution Services Planning Center
DST     Digital Signal Translator
DSU     Data Service Unit
DSX     Digital Service Cross-connect
DT      Distant Terminal
DTU     Digital Test Unit
E       Ear
EASOP   Economic Alternative Selection for Outside Plant
ECCR    Exchange Customer Cable Record
EEC     Electronic Equipment Enclosure
EEC     Equipment Engineering Center
EFPA    Enhanced Feature Package A
EFPB    Enhanced Feature Package B
EFPC    Enhanced Feature Package C
EFPD    Enhanced Feature Package D
EFRAP   Exchange Feeder Route Analysis Program
EJO     Engineering Job Order
ELIU    Electrical Line Interface Unit
EMO     Expected Measured Loss
EOC     Embedded Operations Channel
ES      Errored Seconds
ESD     ElectroStatic Discharge
ESF     Extended Super Frame
ESPORTS Extended Super POTS
EWC     Extreme Worst Case
EWO     Engineering Work Order
FA      Feeder Administration
FAC     Facility Assignment and Control Center
FACS    Facility Assignment and Control System
FAP     Facility Analysis Plan
FCS     Frame Checking Sequence
FCU     Fan Control Unit
FDI     Feeder Distribution Interface
FDL     Facility Data Link
FE      Far End
FELP    Far End LooP
FEMF    Foreign Potential
FEXT    Far End Crosstalk
FITL    Fiber In The Loop
FL      Fault Locating
FLTA    Fault Locate Test Adapter
FPA     Feature Package A
FPB     Feature Package B
FPC     Feature Package C
FPD     Feature Package D
FPS     Framing Pattern Sequence
FSM     Fiber Service Module
FSR     Frequency Selective Ringing
FSS     Fiber Service Shelf
FTTH    Fiber To The Home
FX      Foreign Exchange
FXO     Foreign Exchange Office
FXS     Foreign Exchange Station
GNE     Gateway Network Element
GS      Ground Start
HDIC    High Density Interconnect
HDOS    High Density Optics Shelf
HDT     Host Digital Terminal
HTR     Heater
IBN     Integrated Business Network
IDCU    Integrated Digital Carrier Unit
IDF     Intermediate Distributing Frame
INA     Integrated Network Access
IOP     Input/Output Processor
ISD     Isolation Diagram
ISDN    Integrated Services Digital Network
ISLU    Integrated Services Line Unit
ITH     Integral Test Head
LAC     Loop Assignment Center
LAN     Link to Alarm and Networks
LBO     Line Build Out
LBRV    Low Bit Rate Voice
LCRIS   Loop Cable Record Inventory System
LDS     Local Digital Switch
LDU     Load Distribution Unit
LEC     Loop Electronic Coordinator
LED     Light Emitting Diode
LFACS   Loop Facility Assignment and Control System
LFC     Line Feeder Converter
LFU     Line Fuse Unit
LIC     Lightguide Interconnect Cable
LIT     Line Insulation Test
LIU     Line Interface Unit
LM      Loop Multiplexer
LMOS    Loop Maintenance Operating System
LOF     Loss Of Frame
LOS     Loss Of Second
LP      Low Power
LRAP    Long Route Analysis Program
LRD     Long Route Design
LROPP   Long Range Outside Plant Plan
LRT     Local Remote Terminal
LS      Loop Start
LSI     Line Side In
LSO     Line Side Out
LSS     Loop Switching System
LSU     Line Switching Unit
LT      Line Terminal
LTC     Local Test Cabinet
LTD     Local Test Desk
M       Mouth
MC      Maintenance Center
MCC     Master Control Center
MD      Manufacture Discontinued
MDF     Main Distributing Frame
MDS     Metallic Distribution Shelf
MH      Man Hole
MIU     Metallic Interface Unit, Maintenance Interface Unit
MJ      Major
MLT     Mechanized Loop Testing
MM      Material Management
MN      Minor
MPP     Miscellaneous Pair Panel
MR      Meter Reading
MSDT    Multi-Services Distant Terminal
MTS     Message Telephone Service
MVEC    Majority Vote Error Correction
MWC     Maintenance Work Center
MWG     Maintenance Work Group
MWI     Message Waiting Indication
MXU     Multiplexer Unit
NAB     Network Alarm Bus
NAIU    Network Access Interface Unit
NCTE    Network Channel Terminating Equipment
NE      Near End
NEXT    Near End Crosstalk
NIDB    Network Interface Data Bus
NIU     Network Interface Unit
NM      New Manhole
NMA     Network Monitoring and Analysis
NPA     Numbering Plan Area
NT      Network Termination
NTEC    Network Terminal Equipment Center
NTP     Non Trouble-Clearing Procedure
OCU     Office Channel Unit
OCUDP   Office Channel Unit Dataport
OHCTL   Overhead Controller
OHT     On-hook Transmission
OIC     Optical Interconnect
OIU     Office Interface Unit
OLIU    Optical Line Interface Unit
ONI     Operator Number Identification
ONU     Optical Network Unit
OOS     Out Of Service
OPE     Outside Plant Engineer
OPS     Off Premise Station
OPS/INE Operations System/Intelligent Network Element
ORB     Office Repeater Bay
OSP     Outside Plant
OSPE    Outside Plant Engineer
OTU     Office Timing Unit
OU      Optical Units
OW      Order Wire
PAM     Pulse Amplitude Modulation
PAU     Power Amplifier Unit
PBX     Private Branch Exchange
PCM     Pulse Code Modulation
PCU     Power Converter Unit
PDC     Provisioning Display Controller
PG      Pair Gain
PGD     Pair Group Display
PGP     Pair Group Planning
PGS     Pair Gain System
PGTC    Pair Gain Test Controller
PIC     Polyethylene Insulated Conductor
PICS    Plug-in Inventory Control System
PMN     Power Minor
PMO     Present Mode of Operation
POTS    Plain Old Telephone Service
PRU     Positive Ringing Unit
PTAB    Port Test Alarm Bus
PU      Power Unit
PWB     Printed Wiring Board
R&R     Remove and Reinstall
RCU     Ring Control Unit
RCVG    Receiving
RDES    Remote Data Entry System
REN     Ringer Equivalency Number
RLS     Repeater Location Schematic
RMU     Remote Measurement Unit, Remote Maintenance Unit
ROS     Remote Operations Service
RPFT    Remote Power Feed Terminal
RSB     Repair Service Bureau
RSM     Remote Switching Module
RT      Remote Terminal
RTS     Remote Test System
RTU     Remote Test Unit
RZ      Resistance Zone
S&E     Service and Equipment
S-E     Signal-End
S/I     Signal to Interference
S/N     Signal to Noise
S1DN    Stage One Distributing Network
S1DP    Stage One Distributing Panel
SAI     Serving Area Interface
SARTS   Switched Access Remote Testing System
SB      Signal Battery
SCC     Switching Control Center
SCCS    Switching Control Center System
SCEC    Secondary Channel Error Correction
SDDF    Subscriber Digital Distributing Frame
SDFI    Subscriber Digital Facility Interface
SDH     Synchronous Digital Hierarchy
SDX     Subscriber Digital Crossconnect
SEFS    Severely Errored Framing Second
SES     Severely Errored Seconds
SF      Super Frame
SFIU    Switching Facility Interface Unit
SG      Signal Ground
SID     System IDentification
SLC     Subscriber Loop Carrier
SLIM    Subscriber Line Interface Module
SM      Switching Module
SMAS    Switched Maintenance Access System
SMU     System Memory Unit
SO      Service Order
SONET   Synchronous Optical Network
SP      Standard Power, Special Protection
SPGM    Suburban Pair Gain Planning
SPGPM   Suburban Pair Gain Planning Method
SPOTS   Special Plain Old Telephone Service
SPR     Superimposed Ringing
SPTS    Signaling Path Test Set
SSC     Special Service Center
SSP     Special Service Protection
SSU     Special Service Unit
STIU    Switching Transmission Interface Unit
STM     Span Terminating Module
STS     Synchronous Transport Signal
SXS     Step-by-Step
SYSCTL  System Controller
T-BRITE T-Basic Rate Interface Transmission Extension
TAD     Trouble Analysis Data
TAP     Trouble Analysis Procedure
TASC    Telecommunications Alarm Surveillance Control System
TASX    Telecommunications Alarm Surveillance and Control System
TAU     Time Assignment Unit
TBCU    Test Bus Control Unit
TBOS    Telemetry Byte-Oriented Serial
TCU     TransCoder Unit
TD      Toll Diversion
TDM     Tandem
TFD     Trunk Distributing Frame
TFIU    Transmission Facility Interface Unit
TGS     Synchronous Timing Generator
THC     Test Head Controller
TIRKS   Trunk Inventory and Record Keeping System
TLWS    Trunk Line Work Station
TMC     Time slot Management Channel
TMT     Transmission Maintenance Terminal
TNO     The New Order
TNOP    Total Network Operating Plan
TO      Transmission Only
TOC     Task Oriented Costing
TOP     Task Oriented Procedure
TPI     Tip Party Identification
TRMTG   Transmitting
TRU     Transmit/Receive Unit
TSI     Time Slot Interchange
TSU     Transmission Signaling Unit
UAS     UnAvailable Second
UIP     User Interface Panel
UL      Underwriters Laboratory
UNICCAP Universal Cable Circuit Analysis Program
USDL    U-interface Digital Subscriber Line
VF      Voice Frequency
VRT     Virtual Remote Terminal
VT      Virtual Tributary
VTU     Virtual Tributary Unit
WATS    Wide Area Telephone Service
WC      Wire Center
WCPC    Wire Center Planning Center
WES     Warranty Eligibility System
WORD    Work Order Record Details
XADU    eXtended Alarm Display Unit
XTC     eXtended Test Controller
ZCS     Zero Code Suppression


+-------------+
| SLC Vendors |
+-------------+


AT&T
12450 Fair Lakes Cir
Ste 302
Fairfax, VA 22033
Phone: (703) 802-3853
Fax: (703) 802-3853
 
+----------------------------------------------------------+
|                                       | SLC-5 | SLC-2000 |
+----------------------------------------------------------+
| Maximum No. Subscriber Ports          |   192 |     768  |
| Remote Terminal (qty. per 7-ft. size) |     3 |       1  |
| Remote Inventory and Diagnostics      |     Y |       Y  |
| Identical Plug-ins for RT and COT     |     Y |       Y  |
| Max. DS1 Span Lines Supported         |    24 |      28  |
| Max. DS1 Span Lines Powered/Protected |    24 |      28  |
| Integrated DS-3 Interface             |     N |       N  |
| Integrated Sonet Interface            |       |    OC-3  |
| TR-008 Compatible Mode                |     Y |       Y  |
| TR-303 Compatible Mode                |     Y |       Y  |
+----------------------------------------------------------+



Fujitsu Network Communications Inc
2801 Telecom Parkway
Richardson, TX 75082
Phone: (800) 777-3278
Fax: (214) 479-6990

+------------------------------------------------------+
|                                       | FDLC | FACTR |
+------------------------------------------------------+
| Maximum No. Subscriber Ports          |  192 | 1920  |
| Remote Terminal (qty. per 7-ft. size) |    4 |    5  |
| Remote Inventory and Diagnostics      |    Y |    Y  |
| Identical Plug-ins for RT and COT     |    Y |    Y  |
| Max. DS1 Span Lines Supported         |    8 |   28  |
| Max. DS1 Span Lines Powered/Protected |    0 |    0  |
| Integrated DS-3 Interface             |    N |    N  |
| Integrated Sonet Interface            |    N |    Y  |
| TR-008 Compatible Mode                |    Y |    Y  |
| TR-303 Compatible Mode                |    N |    Y  |
+------------------------------------------------------+



NEC America Inc
14040 Park Center Rd
Herndon, VA 22071
Phone: (703) 834-4000
Fax: (703) 834-4306

+-------------------------------------------------+
|                                       | ISC-303 |
+-------------------------------------------------+
| Maximum No. Subscriber Ports          |     192 |
| Remote Terminal (qty. per 7-ft. size) |      10 |
| Remote Inventory and Diagnostics      |       Y |
| Identical Plug-ins for RT and COT     |       Y |
| Max. DS1 Span Lines Supported         |       5 |
| Max. DS1 Span Lines Powered/Protected |       0 |
| Integrated DS-3 Interface             |       N |
| Integrated Sonet Interface            |         |
| TR-008 Compatible Mode                |       Y |
| TR-303 Compatible Mode                |       Y |
+-------------------------------------------------+
 


Northern Telecom, Inc.
Northern Telecom Limited
8220 Dixie Road
Suite 100
Brampton, Ontario
L6T 5P6 Canada
Phone: (905)863-0000
Phone: (800)4-NORTEL

+-------------------------------------------------------------------+
|                                       | DMS-1 Urban | Access Node |
+-------------------------------------------------------------------+
| Maximum No. Subscriber Ports          |         544 |         672 |
| Remote Terminal (qty. per 7-ft. size) |           0 |           1 |
| Remote Inventory and Diagnostics      |           Y |           Y | 
| Identical Plug-ins for RT and COT     |           Y |           Y |
| Max. DS1 Span Lines Supported         |           8 |          28 |
| Max. DS1 Span Lines Powered/Protected |           8 |           0 |
| Integrated DS-3 Interface             |           N |           Y |
| Integrated Sonet Interface            |           N |           Y | 
| TR-008 Compatible Mode                |           Y |           Y |
| TR-303 Compatible Mode                |           N |           Y |
+-------------------------------------------------------------------+
 



RELTEC Corp
5875 Landerbrook Dr
Cleveland, OH 44124
Phone: (216)460-3600
Fax: (216)460-3690
+----------------------------------------------------------------------------+
|                                       | DISCS 1 | Sonet DISCS | DISCS FITL |
+----------------------------------------------------------------------------+
| Maximum No. Subscriber Ports          |     672 |        2016 |          0 |
| Remote Terminal (qty. per 7-ft. size) |     672 |         672 |        672 |
| Remote Inventory and Diagnostics      |       Y |           Y |          Y |
| Identical Plug-ins for RT and COT     |       Y |           Y |          Y |
| Max. DS1 Span Lines Supported         |      28 |          84 |         84 |
| Max. DS1 Span Lines Powered/Protected |       0 |           0 |          0 |
| Integrated DS-3 Interface             |       N |           N |          N |
| Integrated Sonet Interface            |       N |           Y |          Y |
| TR-008 Compatible Mode                |       Y |           Y |          Y |
| TR-303 Compatible Mode                |       Y |           Y |          Y |
+----------------------------------------------------------------------------+
 


Siescor Technologies, Inc.  (A division of Raytheon)
Box 470580
Tulsa, OK 74147-0580
Phone: (918)252-1578
Fax: (918)252-2757
E-Mail: seiscor@raytheon.com
+-----------------------------------------------------------------------+
|                                       | FiberTraq | S-24DU | RLC-1920 |
+-----------------------------------------------------------------------+
| Maximum No. Subscriber Ports          |           |        |     1920 |
| Remote Terminal (qty. per 7-ft. size) |           |        |          |
| Remote Inventory and Diagnostics      |           |        |          |
| Identical Plug-ins for RT and COT     |           |        |          |
| Max. DS1 Span Lines Supported         |           |        |          |
| Max. DS1 Span Lines Powered/Protected |           |        |          | 
| Integrated DS-3 Interface             |           |        |          |
| Integrated Sonet Interface            |           |        |          |
| TR-008 Compatible Mode                |           |        |          |
| TR-303 Compatible Mode                |           |        |          |
+-----------------------------------------------------------------------+

----[  EOF

