Zines/phrack/12/6.txt

                             Written March, 1987

                               ==Phrack Inc.==

                     Volume Two, Issue 12, Phile #6 of 11

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               ||       CSDC - Hardware  Requirements        ||
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Preface:
========

     This is the second part of my CSDC (Circuit Switched Digital Capability)
series, the first being in PHRACK X. It is suggested that you read the first
part and also the file on PACT in PHRACK XI. If I feel the material was not
covered completely, I will make a third addition to this file.


Hardware Interfaces
===================

     A NCTE or equivalent network interface equipment, located on the customer
premises, is required to provide the CSDC feature for a customer. The NCTE or
an equivalent circuit, located on the customer's premises, is required to
provide TCM (Time-Compression-Multiplexing) transmission on the 2-wire
subscriber loop. The NCTE also has a remote loopback for testing from CSDC
central office.
     Dedicated 2-way CSDC trunk circuits are provided via DCT (Digital Carrier
Trunk) combined alternate data/voice (CADV) units with DCT supervision. MF and
CCIS signalling is allowed on these trunks. They provide signalling, switching
and trunking functions between 1A ESS switch and other CSDC offices. To
provide CSDC, the DCT bank must be equipped with alarm and digroup control
units. A Digital Office Timing Supply (DOTS) is needed to provide network
synchronization for the CSDC feature. A minimum of 3 CSDC maintenance circuits
are needed for the CSDC feature to operate. The circuit provides digital
signals for testing CSDC trunks and loops. They also provide a test
termination for incoming CSDC calls. If an office has superimposed ringing for
4 and 8 party lines, these ringing circuits may be used for loop testing with
the maintenance circuit.

Remote Switching System
=======================
The RSS remote frame contains eight special service slot positions that can be
used for D4 type plug in units (basically allows the RSS to have CSDC
abilities). This allows the CSDC TRXS (Time Compression Multiplexing Remote
Subscriber Exchange) channel units to be housed in the RSS frame. The CSDC
feature is provided via the RSS T1 carrier facilities. The T1 carriers for
CSDC service terminate with position 1 and 0 at the RSS. A ringing and tone
plant is required in the RSS office to ring the phones of special service
channel unit subscribers.


Operation of the CSDC
=====================

     An off-hook origination initiates the seizure of an originating register.
A line translation is performed and the CSDC indicator is received from the
Line Equipment Number Class (LENCL) and is stored in the register. A touch
tone service receiver is connected to the line and dial tone is applied. Upon
receiving a digit, dial tone is removed. If the first digit is a '#', digit
collection is set up to collect 2 more digits. Upon receipt of the 2 digits
(99), the PACT (Prefix Access Code Translator) is indexed via the dialed
digits to determine what service has been requested. If the line cannot have
CSDC, an error message is sent. The AB digits (carrier selection) are
collected next. Once the AB digits have been determined to be valid, the CCOL
(Chart Column) is received. The CCOL merely is a code to tell the PACT what is
to be done. Once the AB digits and the CSDC CCOL is received, the original
register is overwritten with the CSDC CCOL. The CSDC office then sends a bit
down the line to tell the equipment that a CSDC call is being processed.
     The call is now reinitialized to appear as though no digits have been
collected. Digit collection proceeds until the proper number of digits (7 to
10) has been received. An AMA register is seized at the end of the dialing.
The call is then routed according to the dialed digits on a CSDC outgoing
trunk. Answer guard timing for CSDC calls is 800 ms. Upon answer, the answer
time is recorded in the AMA register.
     An outpulsing trunk is seized and a POB is hunted. If an outgoing trunk
and outpulsing device are needed, one will be hunted. Information on the trunk
is stored and a transfer to the outpulsing routine (MF or CCIS) is done. A
verification insures that both calling and called parties are CSDC allowed. If
they are not, the call is routed to an Automatic Intercept Service (AIS).
     For MF outpulsing, a junior register is seized, the outgoing trunk is put
into the proper states, and start pulsing signal detection is done followed by
digit outpulsing. For CCIS, call processing is the same as a normal call but a
CCIS continuity check is performed while on the on-hook state.
     For an incoming call, the CSDC bit from the Trunk Class Code (TCC) is
stored in the incoming register and a CSDC count is pegged. Digit collection
is performed and a terminating DN translation is performed. Ringing is applied
normally and once it has been answered, the incoming trunk is put in the
off-hook state to pass answer to the next office.
     Standard disconnect and trunk guard timing is performed on CSDC calls
when the called or calling party goes off-hook after a talking path has been
established.


Standard CSDC Dynamics
======================

Call forwarding codes dialed after the CSDC code result in reorder.

The Call waiting option is also suspended when a CSDC call is in progress.
Busy tone is given to POTS call that terminates to a CSDC connection. Busy
tone is also given to a calling CSDC party if it encounters a busy line.

In order to have a 800 CSDC feature, the office must have CCIS INWATS ability
in the OSO (Originating Screening Office).

Dialing 911 after the CSDC code is allowed, but 411/611 calls are routed to
error messages.


NCTE (Network Channel Terminating Equipment)
============================================

As covered in Part 1, the NCTE is the equipment that you need to have CSDC.
The NCTE is a piece of hardware that is connected to the CO loop and a
terminal. On the terminal, there are 8 jacks for 8 pins on the NCTE. The
functions of each pin are as followed.

     1 - TRANSMISSION DATA
     2 - TRANSMISSION DATA
     3 - MODE CONTROL
     4 - MODE CONTROL
     5 - TIP VOICE
     6 - RING VOICE
     7 - RECEIVED DATA
     8 - RECEIVED DATA

==============================================================================


This ends PART II of the CSDC series. Since Taran King was in such a hurry, I
will finish the 3rd file with SCCS integrations, loop structure and RSS
structures.

If you have any questions about this file or any other file, please leave me a
message on either...

Phreak KlassRoom 2600 = 806-799-0016  LOGIN:EDUCATE

My Voice Mail Box     = 214-733-5283