TUCoPS :: Phreaking Technical System Info :: mdabrd.txt

BT Abbreviations and Decriptions

         .o Abbreviations & Descriptions Abbreviations & Descriptions 
iNFERNO 1995 

I have written the following as a guide to BT abbreviations and as a
to the workings of system X as it contains a lot to do with that and 
various infomation which could be used at a social-engineering level,
if you're like me, simply intrest (or obsession??).. 

AAS Automatic Announcment Subsystem. Not used in trunk exchanges 
because it is done by the SIS in a trunk exchange. In a local 
exchange it provides the recorded announcements (`Voice Guidance') 
whilst the DS3 provides the tones. 
ASU Advanced Services Network (FeatureNet) 
ATE Automatic Telephone Exchange 
AUS Access Utility Subsystem 

CAS Call Accounting Subsystem. Uses the caller infomation to charge 
the subscriber for a call and then increments the callers record 
table. (the record table is a software version of the subscribers 
CCS Call Connect System. 
CNI Calling Number Interception 
COW Clerk Of Work 
CPS Call Processing Subsystem. The functions of the CPS in the local 
exchange is the same as it would be on a trunk exchange. It has 
overall control over any call. It registers the state of line 
from the subscriber (busy/free etc..), Stores class of Service 
(out going barred, incoming barred etc..), controls the star 
facilities, controls time outs and communicates with other 
software such as the call accounting subsystem. 
CROL Cable running out list 
CSO Contract Supervising Officer 
CSS Customer Services And Systems 

 DCD Data Compiler/Decompiler 
DCD LOOP The process of Decompiling data and feeding the output in as
input to the compiler. 
DCCE Digital Cell Center. This is an exchange that : 
a) Provides service to its own customers and act as parent for 
b) Act as a parent for analogue exchanges, terminating analogue 
line plant and performing call charge as required. 
c) Concentrate and foward traffic to the DMSU for parented 
Analogue Local Exchanges (ALE) without their own DMSU links. 
d) Switch Tandem Traffic Between other DLSUs. 
DDSN Digitally Derived Services Network. (0800, 0891 etc...) 
DJSU Digital Junction Switching Unit. This is a switching unit in a 
high telephone density local network which performs a tandem 
switching function, but has no customer connections. 
DLSU Digital Local Switching Unit. General term for Digital Local 
Processor Exhchange. It provides service for it's customers. 
It can also provide other facilities dependaent on it's role as 
either a DCCE or DLE. 
DLE Digital Local Exchange. This is a DLSU which may host RCUs as in 
a) for DCCEs and also act as a parent for those ALEs which will 
be replaced by RSUs parented upon the DLE as in b) and c) of 
DMSU Digital Main Switching Unit. Provides a fully interconencted Trunk 
Network. Each DMSU catchment area will compromise of several old 
GSC areas. The DMSU will switch traffic bother between and within 
the catchment area. 
DMU Dialled Meter Unit. 
DN Directory Number 
DPLE Digital Principle Local Exchange. Main exchange for an area. 
DS3 Digital Subscribers Switching Subsystem. This is in principle the 
same as the RCU yet it is situated inside the exchange - both are 
usually called subscontractors. It is used to connect subscribers 
to the local exchange. They are connected via PCM links. 
DSG District Support Group (BT District Staf) 
DSS Digital Switch Subsystem. The DSS carries out all the switching 
functions on a System X exchange - Trunk or local. 
DSSS Digital Subscribers Switching Subsystem. See DS3. 
DWI Display Work Instructions - A common found trash. 

ERS Emergency Repair Service 
END Exchange name documentation 

FMR FaultMan's Ringback. Dial the FMR (3 digit starting with 1 - 
generally 17x) number and replace handset, upon ringback the 
service should provide a quick analysis of any problems. 

HTD Hardware trial period - minimum 5 mins 

IDDF Intermediate Digital Distribution Frame 
ISDN Intergrated Services Digital Network. 
ISIS Inland Services Infomation System. ISIS is basically a book and 
manual service. Within ISIS it is possible to find infomation 
through indexing. Coding is AAA/BBB/Cxxx. AAA = Discipline, 
BBB = Main Subject, C = Tertiary Function/Specialism, 
xxx = document number. 
AAA - listing approx 30 disciplines eg, Personal, Transmission, 
Operator Services, Customer Services etc.. 
BBB - Listing approx 150 main subjects within the respective 
disiplines eg Employment, Optical Fibre systems, Operating 
procedures etc.. 
C - Listing approx 500 functions of specialisms within their 
respective main subjects. E.g Recruitment, Planning & 
Implentation etc.. 
EXAMPLE = CSS/CCS/C010.. installation practice for mini master 3. 
ISOS In Service Operational Support (Manufactures Staff). The ISOS 
would be called in when an urgent problem needs a higher level of 
support, or if a major service failure occours they can be called 
in quicker than the PSG. 

 LLE Large Local Exchange. 
MCO Maintenance Clearence Officer. OMU worked responsible for making 
sure all tasks and routines have been carried out. 
MCS Maintenance Control Subsystem. Carries out maintenance functions. 
MLE Medium Local Exchange. 
MMIS Man Machine Interface Subsystem. The MMIS allows engineers to 
control and manage the exchange through VDT's etc.. 
MPCS Multi Party Connection Subsystem. The MPCS allows 3>10 subscribers 
to be connected together at the same time. 
MRA Malfunction Reporting Alarm 
MSS Management Statistic Subsystem. Keeps records of the junction 
routes in the local exchange and keeps traffic records for DS3s 
and RCUs under it's control and also for the AAS. 
MTS Message Transmission Subsystem. Terminal part of CCS (not to be 
confused with CSS) link. It transmits and recieves messages sent 
between distanct CPSs (Call Processing Subsystems) and carriers 
out error checks on messages and re-transmits if necessary. 
MTS MsgFor The MTS message format is : - Error Check, Message, Routinglabel, 
header. The header contains the message number incase a resend is 
needed, the routing label includes the OPC (Originating Point 
Code) which identifys the originating exchange and the 
Destination Point Code (DPE) which identifies the destination 
exchange. The message tells CPS what it has to do and the error 
check obviously checks the message for errors. 

NSS Network Synchronisaton Facility 

OIM Operation & Maintenance 
OMC Operations & Maintenance Center. BT policy requires this, collects 
data from exchanges and monitors data for presentation for the 
OMC staff (Traffic, Sales, Operation & Maintenance Unit. (OMU) ) 
OMU Operation and Maintenance Unit. Room where engineers moniter the 
performance of the exchanges, and recieve data collected my the 
OMC. There is one or more connected to each OMC. OMU staff can 
send data to the OMC to control the exchanges conneted to it. 

PABX Private Automatic Branch Exchange 
PACE Plessey Automatic Commisioning Equiptment 
PBX Private Branch Exchange 
PCM links A maximum of 30 channel PCM systems coontect to the DSS which 
gives 240 speech channels (8x30) which are available to 2048 
PLEXUS/SDF Computer center with both ICL and PLEXUS systems 
PRAT Primary rate access terminal 
PSG Product Support Group (BT Headquarters Staff). PSGs can be called 
in if there is a problem on site. They give the authority for any 
emergency design modifications carried out without authority 
having being gained in advance. 
PSU Power Supply Unit 
PUS2 The Central Processor which provideds the processing power and 
storage facilites for all other subsystems. 
PXSM Pre-Extension Site meeting 

 RALP Remote Alarm lamp panel 
RCC Remote Concentrator Centre. Point with many RCU's. 
RMCC Remote Multi-Concentrator Unit. Two or more subscribers connected 
in a RCC. 
RCU Remote Concentrator Units. These must be connected to the DLSU and 
are considered as part of the DLSU to which they are connected. 
The RCU is situated away from the Telecom building in a more 
convienient place and it is the apparatus that divides the lines 
and gives them their equiptment numbers. If there is no 
connection between the RSU and the exchange then customers may 
still call numbers controlled by the RSU but not outside. Charge 
Handling is handled at the TE so if there is no connection to 
the TE there is no call charge. Telecom uses a standard two RCUs 
for security reasons. 

 SALT Subscribers Automatic Line Testing. For System X and Y exchanges. 
The code for this is generally 175 and has the same job as the 
FaultsMans Ringback but is more advanced with increased options 
after the ringback. 
SDP System data page 
SPM Customer's Private Meter 
SIS Signalling Interworking Subsystem. Used as an interface between
system X exchange and analogue exchanges. It convers analogue to 
30 channel PCM for connection to the DSS. In like local exchange, 
unlike to trunk exchange it does not send tones or annoucments - 
the AAS does. 
SIU Slide-In-Unit 

TE Telephone Exchange/Terminating Equiptment 
TNS Test Network Subsystem. The TNS controls the accessing of and 
testing of all digital and analogue junctions and subcriber lines. 
It uses SIS to access analogue junction lines, DSS to access 
digital junctions and DS3 tto access subscribers lines. 
TXD #'s A method of labeling types of exchange by number that forms
of the exchange's Network Nodal Identity which appears on all 
documents specific to the particular exchange. 
3 RCU (System X) 
5 UXD5 
6-9 DLSU (System X) 
13 DMSU 
14 DJSU 
30 OSSU 
31 OCHC 
53 RSU (AXE 10) 
56-59 DLSU (AXE 10) 
80-86 OMC 

 UM Unit Manager. The UM is responsible for the service given by the 
TXD exchanges in his OMC area and the organisation of staff. 
UXD5 Digital Exchange developed from the CDSS1 (Monarch) PABX. 

 VRS Voice Response System. Allows remote testing of subscriber's 
line gived number and code. There are possibly other 
systems under the heading VMS because it's not exactly 
very use specific. 

WMS Work Manager System. Used by BT engineers to download their 
infomation for jobs of the day. Generally used via a portable 
field terminal and acostic coupler. It is accessable from any 
termination point in England. 

XD ExDirectory. 

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