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10/5/2009
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| Information on these pages copyright of Ian Dufour | If you use this Encyclopedia regularly please make a donation to Tearfund |
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C
C can represent temperature or a capacitance but here C is a programming language, developed by Bell Laboratories for processing-intensive applications. It was originally produced to avoid the exclusive use of assembly code with the UNIX operating system. It is very fast, powerful, flexible and efficient. C++, also developed at Bell Labs, took most of the advantages of C and added capability for object-oriented (OO) programming. C++ is a superset of C.
The ubiquitous form of common-channel signalling in telecommunications networks is known as the Signalling System Number 7, or SS7, sometimes still called C7. This is an ITU-T standard but the ITU was previously known as the CCITT and the term CCITT Signalliing System No 7 was shortened to C7. See Signalling.
A generic term for an external housing containing telecommunications equipment. It has traditionally contained a cross-connection point for copper pairs in the access network (between the "E" side going to the exchange and the "D" side - distribution side - going to the customer). A cross-connection point provides a flexibility point and a means to minimise the number of spare pairs back to the exchange thus improving the utilisation on the "E" side. More recently cabinets contain active electronics for digital systems and are used for cable-TV electronics as well as in the traditional telephone network. Cabinets are a ubiquitous part of street furniture in many parts of the world.
The first telecommunications over distance relied on open wires suspended between telegraph poles but the limitations of expanding this soon became apparent and wires were bundled together and enclosed in a sheath and called a cable. Cables came in a variety of types including pair-type cables for local network use built up from units of pairs, quad-type cables formed in quads and layers for longer distance use, carrier cables with screened pairs for early TDM systems, co-axial cables for long-distance high-capacity TDM systems and, more recently, co-axial cables for Cable TV systems and optical fibres.
Wire conductors have been predominantly copper but over the years there has been some experimentation with alloys and in particular aluminium conductors.
Sheaths were initially lead but moved later (post-WWII) to polyethylene with a metallic moisture barrier under, and bonded to, the polyethylene sheath.
Cable can be suspended between poles (called aerial cables), laid direct in the ground, sometimes using a mole-plough or, most commonly in the UK at least, pulled into ducts (known sometimes as conduits). Cables exist in an extremely hostile environment, including long-term immersion in water and pollutants, and their design must take this into account. Cables are installed in limited lengths which must be jointed together at both the conductor or fibre level and at the sheath level to withstand the same hostile environment over long periods. Joints in underground ducted cables are made at jointing chambers or manholes. The people installing and maintaining cables must comply with rigorous and well tested safety procedures including roadworks protection and testing for gases in underground structures.
Cable-TV has its roots in the delivery of a small number of analogue TV channels unidirectionally over co-axial cables. It has evolved to cover the delivery of multi-channel interactive digital-TV together with telephone services and broadband Internet services - the so-called triple play. The technology has evolved to include hybrid fibre-coax, as well as the inclusion of more traditional copper pairs. In the UK the development of cable-TV to compete in the traditional areas of telecommunications was encouraged by Government regulation through asymmetric competition rules that were only relaxed at the turn of the century. These allowed the cable-TV operators to move into telephony and Internet whilst prohibiting the incumbent from delivering TV programmes. To add to the competitive environment the UK was one of the first to also encourage the delivery of multi-channel digital-TV channels directly to the home by satellite. Other countries have different backgrounds and competitive and regulatory environments but the cable-TV operators in many have also become major operators in telecommunications.
Many of the technologies in the core of the network, including circuit-switching and packet data networks use common telecommunications technologies and designs but the access delivery of TV channels and Internet uses a significantly different approach. This technology has its own specialist supporting vendors and its own terminology, including head-ends and set-top boxes as well as paying great attention to band-planning, signal-splitting and issues such as noise and distortion allocations for the cable systems themselves. See Cable Technology for local access, BTTJ Vol 16, No 4.
A way of storing information in a computer memory, or on a server in the network, so that the information can be accessed more quickly than going through the normal processes and to the original source of the information. The storage area of the computer or network server is referred to as cache memory. The data in a cache memory is usually held temporarily - the time period suits the application and can vary from a single session to weeks or months.
A noun or a verb. As a noun it has many definitions but by history and common usage it means a telephone connection with two people talking. There are data equivalents in the connection orientated environment (such as ATM) but it is not really applicable to the connectionless environment where session is a better term. The verb, to (make a) call, implies setting up a call. Call minutes is a key concept where the call duration is metered and charged because monitoring call minutes is a guide to financial income on the one hand and the dimensioning of systems (traffic engineering) on the other. There are a variety of technical call processing issues in switching systems associated with call set-up and clear-down. See also call control.
A collection of operators, usually called agents, who answer, or make, calls in a methodical way. Examples for handling incoming calls include helpdesks, responses to television selling advertisements and directory enquiries. An example of outgoing calls is of a telemarketing centre selling kitchen refurbishments. Generally the agent works to a script on a computer screen, adding information as relevant. Also generally, a call-centre is a physical place housing the agents and their managers but in theory, and occasionally in practice, the agents can be distributed, such as working from home. A call-centre can be placed in any location to which the calls can be routed - call centres handling UK customers can be found as far afield as India and the Philippines. Distance location provides challenges on time zones, culture, knowledge and language that have been successfully met.
Technically there are a number of challenges in automating the call handling process to minimise ineffective time (where seconds count in high throughput situations) and maximise the number of calls handled by each agent. The flip-side of this is less control by the agent leading to stress and high turnover of agents incurring retraining costs. Steering a path between these is a key part of the design of call-centres. Relevant technologies include automatic call distribution and computer/telephony integration (CTI). In advanced systems the calling line ID is used by the CTI to bring the customer's data up on the screen in front of the agent as the call is answered. Although this is not infallible because the ID is for a telephone number and not a person it works well with calls mainly made by individuals from their homes and reduces handling time considerably.
Call-control is about establishing, maintaining and ceasing the connection required for a telephone call. Much of this is a basic function of the circuit-switched telephone exchange but it gets more complex for advanced services using intelligent network (IN) capabilities and for calls using partly connectionless elements in the call (such as voice over IP).
The end of a communications channel at the receiving end of a new call or session originated by a calling party.
A generic, and in some countries a proprietary, name for a credit-card sized card used for making calls that are charged to a specific account when away from base. Also known as a charge card. The services associated with a calling card are often referred to as card services or cashless services. They are typically used by business people when travelling to charge calls to their company, or by consumers for charging calls to their home account. The use of calling cards was made possible by the introduction of intelligent network capabilities allowing for the identification of the card, the forwarding of the call to the required number and the allocation of the correct billing data. However, they achieved a peak in the late 1990s before the widespead use of mobile phones vastly reduced their use for telephony calls.
A calling line identification marker can be carried by a call in an enabled system so that use can be made of it - such as the display of the calling number or the association of data with the call in a call-centre.
The end of a communications channel originating the call or session. The other end is the called party.
A contraction of 'capital expenditure'. Generally this is the money paid out for the installation of plant for the network and its support systems, which thereafter become assets. It is usually for tangible hardware but most systems other than external plant now include software. The treatment of software purchases in financial statements can vary and much depends on its 'life'. Where the software is expected to be maintained but kept for the life of the equipment it is generally capitalised and depreciated with the same life as the equipment. Where the software is for use over a short duration it is usually 'expensed' which means it is attributed to current account expenditure, sometimes known as currex.
Services associated with a calling card.
A company providing communications capabilities and services. Also a radio signal, as a contraction of carrier wave or CW, which is capable of being interrupted at a slow rate to pass information (e.g. using Morse code) or being modulated with additional information.
Carrier cables were used for carrier systems where fdm transmission was routed over two dedicated cables laid alongside each other, one for each direction of transmission. The first 12-channel system in the UK, between Bristol and Plymouth, used two low-capacitance 19-pair cables installed about 1935 with the pairs in simple twin formation. Subsequently, 24-pair cables in quad formation became standard. Despite some development of carrier systems the cables were not widespread as they were superseded by long-distance multi-channel co-axial cables which in turn were superseded by optical fibres. However, after the recovery of the carrier systems the cables were used to carry 8 Mbit/s digital systems in the early 1980s as part of the initial stages of the digitalisation of the long-distance transmission network.
A telecommunications operator owning and operating a telecommunications network of which a significant proportion of the capacity is leased to other telecommunications operators.
A general term used to distinguish large-scale network capabilities with many users, rather than smaller-scale networks such as enterprise networks or home networks. Carrier-scale is generally distinguished by having millions of end-users with a network that is scaleable, manageable, performant, reliable and secure.
A system long since superseded where fdm analogue transmission was routed over copper pairs. The first UK carrier system in 1932 was the forerunner of later access systems in that it provided only one extra carrier circuit, albeit then over an existing pair of overhead wires. The first applications to copper cables was in 1935 providing one extra circuit over an existing 4-wire audio circuit. By 1937 systems provided 5 extra circuits over pairs in a quad cable separated by at least two layers. This represented the limit for one cable working and subsequent systems used two carrier cables permitting first 12-channel systems and finally 24-channel systems until they became obsolete through the adoption of co-axial cables and systems from 1950 onwards (later themselves overtaken by optical fibre cables and systems). The work on early carrier systems established the basic speech-band channel of 300 - 3,400 Hz that persists today and also for the fdm group and supergroup hierarchy (now mainly obsolete). All the equipment was valve (vacuum tube) operated. Years later in the late 1970s onwards the use of relatively low-cost solid-state 1+1 carrier systems in the local loop allowed the provision of new exchange lines when there was a shortage of copper pairs in cables for new customers. Deployment of the 1+1 carrier systems deferred the provision of a costly new cable. Variants of these, using digital techniques, continue today.
Stages (CS1, CS2 etc) of the service capabilities of the implementation of intelligent network (IN) standards.
CCIR (archaic)
The forerunner of ITU-R
CCITT (archaic)
The forerunner of ITU-T. Still occasionally living-on in reference to Signalling System No 7 sometimes known as C7, short for CCITT No 7 or more properly CCITT Signalling System No 7 (SS7) as it was once known.
North American standards for cellular wireless systems. See also Code Division Multiplex
Part of a battery of cells providing a portable power source.
The geographic area covered by a base-station transceiver in a cellular radio system.
The basic unit of a cell-switched system such as ATM .
Cellular/Cellular wireless systems - See cellular wireless systems.
A term originating in the US for a local telephone exchange, i.e. a switching centre for voice telephony with direct connections to customers through the access network.
One of a pair of words at the centre of the telecommunications and IT businesses - the other word of the pair is distributed. Not only do they apply to the design and use of technology but they apply to the organisation of operations as well. Debates about the merits of the two approaches in various situations have occupied past and present generations and there is every sign that the same will be true for generations to come. Some examples are that intelligent networks are centralised whilst the Internet has distributed intelligence; that main-frame computers are centralised whereas PCs are a distributed system; and that fault handling centres are best centralised to take maximum advantage of scale versus localised centres to maximise response times and local knowledge.
A telephone service, provided by an operating company to a business user, having capabilities similar to those provided by a PBX but provided from the local telephone exchange.
Usually a covered jointing chamber just below the surface of the street for accessing underground external cables and for housing the joints between separate cable lengths or for providing a spur cable from the main cable. A larger chamber accessed by a shaft is generally called a manhole (or, in the US, a vault).
Monitoring, recording and assessing changes to the scope or timing of project management with the aim of making all those involved fully aware of the effects on cost, time and performance before making the changes.
A form of signalling where the signalling information is directly associated with the channel carrying the main signal. The other main form of signalling is common-channel signalling.
Charge card - see calling card
Circuit switching
Manual switching for telephony, was the first type of one form of switching now known as circuit-switching, because a dedicated end-to-end connection - or circuit - was allocated to the call for its duration. Circuit switching is therefore connection-oriented (but not all connection-oriented switching is circuit switched). Manual switching was followed by a range of automatic switching technologies.
Network policies that pre-determine classifications of traffic and align network resources with business objectives based on them using quality of service (QoS) criteria. Ports on routers can be configured as trusted or untrusted. On trusted ports QoS uses the received CoS value whereas on untrusted ports the QoS replaces the received CoS values with a port CoS.
A term widely used in computing to refer to the infrastructure that allows distributed computing resources to be used by a company. It generally makes use of desktop computing resources (the clients) to call on various commonly accessible computing resources (the servers) such as data-bases largely independent of location by making use of a local or wide area network (LAN or WAN).
In more complex realisations the roles of client and server are not always obvious, for instance when a server handling a client calls for data from another computer and thereby changes its role to a client role for one transaction. Client/server architectures are widely used within telecommunications systems and applications as well as being a driver for the provision of wide area network services for customers using client/server architectures.
An outside plant term for the means of closing a joint between two lengths of cable. Once the pairs or fibres have been jointed together (or spliced) the integrity of the cable sheaths must be maintained as a continuous barrier against water and foreign-body ingress. This is not as easy as it sounds. In the days of lead sheathed cables the closure would use a lead sheet which was plumbed to the lead sheaths with molten solder. Even this was not certain to provide a leakproof seal. With the advent of plastic sheath cables getting a good seal provided a challenge until the arrival of shrink-wrapped joints using specially treated plastics and adhesives that bonded to the cable sheaths when heated to a certain temperature with a flame, the correct temperature being indicated by changing colour spots on the surface. Thus an age old practice was transformed by the application of modern space-age materials science.
Co-axial cable comprises a core conductor surrounded by an outer conductor at some distance away with a dielectric of air or an insulant in between the two conductors. The downleads from television aerials are a form of co-axial cable and a similar form is used for interconnecting equipment using high-frequencies (e.g. multiplexers) but the main external use in telecommunications today is for cable-TV systems. However, there is a long history of the use of co-axial cables for long-distance transmission, including undersea and transatlantic cables, spanning approximately 50 years from 1938 until the widespread adoption of optical fibre systems first overtook them for new provision and then encouraged their recovery. The earliest UK co-axial cable was in service by 1938 between London and Birmingham and had 4 tubes of 0.45 inches (approx 1.14 cm) diameter, each pair carrying 320 channels built up from groups and supergroups, albeit pre-standard ones. Once the international standards were in place for groups and supergroups these were adopted. Co-axial cables of two main tube sizes - small bore of 1.2/4.4 mm and large bore of 2.6/9.5mm - were used for capacities over each pair of tubes ranging from 600 in 1945 to 10,800 in 1980. The use of valve (vacuum tube) technology peaked in around 1960 with solid-state systems being used thereafter. Power feeding the repeaters called for high voltage systems - 2000 volts between the central conductors of the co-ax pair (1000-0-1000) for valve systems and 1000 volts (500-0-500) for solid-sate systems. These called for special safety practices and the use of tokens after power-down before working on the cables.
Code division multiple access (CDMA)
Code division transmits uniquely identifiable spread-spectrum signals that can be discerned by the receiver. Multiple access is a means by which many individual sources access a shared resource. (other forms of multiple access include FDMA, TDMA and CSMA/CD used by Ethernet). CDMA therefore allows many code division spread-spectrum signals to use a common frequency band and it is generally associated with radio systems, notably with the USA digital standards for cellular wireless systems.
This can mean several things including writing computer programmes. It can also mean encryption where the coded signal is not meant to be read. However, here it is taken to mean a code that is intended to be read and we will define it as the process of converting, or encoding, a signal from one form, such as analogue, into another such as digital. Even this would include the Morse Code but we are really embracing ways of coding signals to facilitate their transmission and/or processing. Such conversions take many forms, including line codes for transmission, coding waveforms (such as PCM) and data compression.
A device which includes the functions of encoding (converting an analogue signal into a digital signal) and decoding (converting a digital signal into an analogue signal). The term is a contraction of coder/decoder. It can be an assembly of components, a chip or a part of a chip.
The world's first programmable electronic digital computer was produced to decipher German codes during the second world war. It first came into use at Bletchley Park in the UK in 1942 and was designed by telecommunications engineers, notably Dr T H (Tommy) Flowers, at the General Post Office Research Station at Dollis Hill, London, the forerunner of BT Exact at Adastral Park. See also history.
A form of signalling where the signalling information for many circuits is aggregated in a single signalling channel, by far the most common realisation being ITU-T Signalling System No 7 (SS7). The other main form of signalling is channel-associated signalling.
In the early days of telegraphy and telephony in the UK there were many companies and individuals seeking to provide service to customers which were consolidated. Since then there have been a number of ebbs and flows.
Telegraphy was introduced by the railways but spread slowly to the public through many small and poorly co-ordinated companies. The Telegraph Act of 1868 gave the Government the power to take them over and the Act of 1869 granted the Postmaster General a monopoly of telegraphic communication after which the growth of telegraph services was very rapid.
Several companies were set up to exploit the invention of the telephone in 1876 and the first telephone exchange was opened in London in 1879. It soon became clear that the telegraph service would have to face severe competition from the telephone. At this point it was established (by the High Court) that a telephone was a telegraph within the meaning of the Telegraph acts and this led to licences for the telephony operators being issued by the Postmaster General.
By 1889 the principal telephone companies had merged into the National Telephone Company (NTC) and in 1892 the Government purchased the trunk (core) network from the NTC, partly prompted by increasing competition to telegraphy revenues, leaving the NTC to local operations only. In 1899 local authorities were permitted to enter local service provision leading to municipal services in 6 cities/towns so that by 1912 local services were provided partly by the NTC, partly by municipalities and partly by the Post Office. Finally, the state took over the whole of the NTC bringing under Post Office control virtually the whole of the UK telephone system.
The Post Office first became Post Office Telephones and ultimately British Telecom - the first of the major European national telephone operators to be privatised following the experience of the Baby Bells. Only the Kingston-upon-Hull municipal system survived intact until today. With privatisation came a new era of deregulation and competition to the extent that there are now numerous competitors in every segment of the telecommunications market - see also regulation/de-regulation).
A compiler is a programme that takes the source code produced by a programmer in a higher level language, such as BASIC, and translates it into instructions understood by the computer (machine code).
Compilers translate large sections of code at a time whereas interpreters translate one statement at a time. Compilers translate the source code into machine code for loading and running on the target computer at a later stage. Interpreters translate each statement into machine code and then run it so they must run on the same machine at the same time as the source code.
Computer Telephony Integration (CTI)
The combination of digital PBX technology with local area networks (LAN) and client/server computing. A concept that is closely allied to call-centres, particularly the handling of data associated with a caller and presenting it to the operator/agent.
Changing a signal in a way that makes better use of a constrained transmission channel whilst being able to be restored (expanded) at the distant end using an agreed algorithm. In analogue systems it is usually aimed at reducing the dynamic range between high level signals and low-level signals. In digital signals it is usually aimed at making the best use of a limited bit-rate channel for maximum information transfer. For example, the Moving Picture Expert Group (MPEG) is a body that has defined a range of data compression standards for moving images, including animation, video and audio, with compression ratios ranging from 4:1 to xx:1. (14 or 200!?)
A composite word made up from compressor and expander meaning a device which takes a signal and compresses it for transmission to line and then receives a compressed signal from line and expands it into its original form. A companded circuit will have a compander at each end. It originally entered use in the analogue form of compression where the aim is to reduce the dynamic range between low level and high level signals but is equally used today in a digital environment where the compression is a form of bit-rate reduction.
The reciprocal of resistance.
Another name for ducting buried beneath the ground to put cables in.
Usually applied to setting up a call ("conference call") or session to allow several people in different locations to be connected together for the purpose of a meeting. The essence of it is multi-point rather than point-to-point.
Audio conferencing is now commonplace and three people can make use of the 3 way calling capability of many switching systems. For larger numbers it is usual to make use of a dial-in conferencing service using a conference bridge. This ensures that the different connections are balanced - and amplified where necessary - to give a similar quality of experience to all the users, even as people join and leave.
Video conferencing implies a similar conference but where people can also see each other as well as speak to each other. It used to entail specialist equipment in studios with people travelling to a studio to participate - it was thus used particularly for transacting international business. Nowadays, video conferencing takes many forms, many of which are multi-media extensions of a voice call conducted from a desktop computer with a small web-camera attached.
A term used in conjunction with networks, software and radios amongst others and synonymous with smart. It implies an ability to change easily but in practice in telecommunications changing one part of a system invariably leads to complication rather than simplicity.
Configuration management is the process of controlling changes to, and the versions of, the constituent parts of a network or system. The physical and functional characteristics of a product or service can be controlled using documents, records and data, especially through the use of an Intranet web-site. Managing configuration involves making sure that changes and variations are put in place only after being authorised. Configuration management applies to new projects and to operational networks and systems. Ref: Configuration management - keeping it all together. BT Technology Journal, Vol 15, No 3.
Congestion occurs when a system has insufficient capacity to carry the required traffic in a given period of time.
A concatenation of transmission channels or telecommunications circuits, switching and other functional units set up to allow the transfer of signals between two or more points in a telecommunications network to support a single communication.
Connection-oriented means that a communications path is set up and used in a way that all communications flow over the same path which is then closed down at the end. The traditional dialled telephone call set up through circuit-switched telephone exchanges is the best known example (connection-oriented circuit-switched). Data versions, such as MPLS, make use of a packet-switching infrastrucure (connection-oriented packet-switched).
Connectionless (applicable to services and networks) means that a connection is not established and is most usually in the context of data transmissions where each data element (datagram) is addressed, sent independently and can then travel over different paths compared to to the following datagram. The data is then reassembled at the far end. The connectionless equivalent of a call is a session.
Continuous professional development
The Engineering Council's definition of CPD is "The systematic maintenance, improvement and broadening of knowledge and skill, and the development of personal qualities necessary for the execution of professional and technical duties throughout the practitioner's working life". Everyone in the telecommunications and computing business needs to remember that the rate of change over a wide field is very significant and if you don't keep up it will go on without you - so have a personal plan to develop your competencies and technical knowledge.
A small text file placed on the hard disk of a personal computer by a visited web-site. Like knives and cars they are mainly used for constructive reasons but occasionally can be misused depending on the goodwill and knowledge of the participants. Most e-commerce sites make extensive use of them to facilitate revisits and add to the user experience, but some sites will look for cookies from other sites to build up a picture of the user. Some people regard the placing of a cookie on their hard disk as a privacy issue and most web browsers have a cookie filter which if switched on will alert the user to cookies about to be placed on the hard disk. However, some sites use so many cookies that operating with such a filter is virtually impossible in practice leaving the user the choice of accepting them unconditionally or moving away from the site.
Object oriented computing is a way of supporting distributed data processing. Objects encapsulating data and processing can be distributed across a computer network but there must be a method of locating and accessing the distributed objects and of using them irrespective of which programming language they are written in or what operating system they run on. The Object Management Group (OMG) developed a set of standards for the use of objects of which the first was the Common Object Request Broker Architecture - or CORBA. The broker allows applications to request services from objects without knowing anything about their location.
corDECT is a wireless local loop (WLL) technology, jointly developed in India by two companies and the Indian Institute of Technology (IIT) Madras (in Chennai). Based on the Digital Enhanced Cordless Telecommunications (DECT) standard, corDECT provides cost-effective, simultaneous high-quality voice and data connectivity in both urban and rural areas. It provides voice communication using 32 Kbps ADPCM, and Internet connectivity at 35/70 Kbps.
This concept was originally aimed at the telephone terminal on the fixed network for both residential and office use. There is a base station connected to the telephone cabling and to a power source, and a removable handset which charges its battery when on the base station. When removed the user can make and receive calls at distances away from the base station ranging up to about 50 metres. There are a number of analogue standards for cordless telephones and one significant digital standard - DECT - which also forms a part of the ITU IMT2000 set of standards (a cellular wireless system).
The distinctions between cordless and cellular and between telephony and data uses are thus starting to blur. Is a wireless link between the terminal device and the network only cordless when the network it connects to is within in-premises wiring? corDECT is a case where the DECT technology is used for serving a number of users for speech and data over several km. Cellular radio handsets connect to a base station (BSS) connected to a fixed network of between some tens of metres up to several km away, but are undoubtedly cordless. A PC or PDA using a wireless LAN (WLAN) is connecting cordlessly to a fixed network over a few tens or even hundreds of metres - some of these are in-premises but others are public 'hotspots'.
Some people think that all terminals will be wireless enabled one day so the first link will be wireless but whether it is called cordless, wireless local loop, WLAN or cellular is not really of any consequence.
In both fixed and mobile circuit-switched networks, the core network is generally taken to mean switching centres and the transmission systems inter-connecting them. The transmission systems also carry data from the packet-switched networks. In the fixed network it has usually been necessary to sub-divide it.
At one stage it was common to refer to the junction and main networks. The junction network comprised the local exchanges and the transmission systems linking them to the main or trunk switching centres. The main network comprised the trunk switches and the transmission systems linking them.
Nowadays it is more common to refer to the outer core, or backhaul, network, and the inner core network respectively. The inner core is distinguished by very high-speed transmission systems, typically at 2.4, 10 or 40 Gbit/s. As packet-switched network transmission requirements have grown to exceed those of speech over circuit-switched networks the same terminology of inner and outer core has also been adopted to fit in with edge and core router topologies. This is described further in Core and backhaul transport, BTTJ, Vol 22, No 2.
A general reference referring to the copper conductors predominantly used in pair-type cables and the systems, such as 1+1 pair-gain systems that use them.
A correspondent relationship refers to the agreement between two countries for suitable rates of remuneration for traffic originating in one country and carried in the other, either transiting or as destination traffic.
A form of circuit switching equipment.
The methods used to break into encrypted messages. Otherwise known as codebreaking.
The process used to turn an easily readable signal (e.g. plain text) into an unintelligible coded signal (called a cipher text) and back again, otherwise known as encrypting and decrypting.
Current account expenditure (i.e expensed and not capitalised - see capex). Sometimes known as opex.
What telecommunications exists for. The person who pays the bill - who is not always the user. In the early days of telephony used to be known as a subscriber - a term which still appears from time to time.
Customer relationship management (CRM)
The main functions of CRM in the context of telecommunications are:
- Handling parties which have not yet bought services with the company – prospective sales, keeping track of customer contacts, and validating new customers (to avoid fraud).
- Supporting the automation of scripted selling, up-selling, managed campaigns.
- Handling orders, enquiries and fault reports from the customer, or from the network/service platform in the case of faults.
- Monitoring and assessing the Quality of Service provided to the customer and comparing it against the agreed service level agreements.
- Analysing customer and marketing data to support future campaigns.
CRM systems need to support a variety of means of communication with the customer, such as via the web, via phone to customer service representatives (inbound and outbound), and via sales people who can download a section of the database to their portable PCs, deal directly with the customer, and then synchronise the main database with their local copy at a later time.
Cyber...
A term usually accompanied by another word implying the Internet or IT version. Examples include: Cyber-crime, Cyber-security, Cyber-space, Cyber-world. The prefix is drawn from the word cybernetics which is the study of communications and controls common to machines and living things.
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