.o Abbreviations & Descriptions Abbreviations & Descriptions iNFERNO 1995 I have written the following as a guide to BT abbreviations and as a guide 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, or, 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 meter) 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 the 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 RCUs. 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 DCCEs. 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 subscribers. 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 a 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 part of the exchange's Network Nodal Identity which appears on all documents specific to the particular exchange. TXD NO 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. Back to document index