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PABXs — the user guide
Data communications and services in the USA Frost & Sullivan, USA (1982) 327 pp During the past seven years or so, EDP user expenditures on data communications, including both line charges and equipment, has increased by 22% annually, on average. According to this market study, this growth rate will be maintained throughout the 1980s, with user budgets at $6400M in 1981 approximately doubling in size to £12 500M by 1985. Data communications will account for an increasing proportion of EDP user budgets, according to the study. The market will be driven by increasing deployment of distributed data processing techniques and the proliferation of remote data-terminal equipment. The analysis of service offerings and their economics in the report lists a variety of choices. Beyond the traditional telephone companies and Western Union, there are: • 11 new common carriers, along with two more satellite-based carriers already approved by the
FCC, scheduled to come into operation before the mid 1980s, • three value-added networks, introduced in the mid 1970s, aimed directly at data processing applications and performing operations on information transmitted, including formatting, speed, code and protocol conversion, • a range of message service offerings, including Western Union Mailgram, Tymnet-Tymegram and FTE/Telenet-Telemail; the new electronic mail services, such as Tymnet-Ontyme; and sophisticated facsimile services that provide code, speed and format conversion between incompatible terminals, such as Graphnet and ITT/DTS-Faxpak services. All such services will gain importance in the future, the report says. In addition, it expects videotext/ teletext developments to have an
P A B X s - the user guide Communications Studies and Planning, UK (1982) 200 pp, £185 This report contains a full user specification of all the PABXs currently approved by British Telecom for connection in the UK. The guide also covers the design of private telephone networks, dimensioning an exchange, implementation and maintenance, the choice between the use of local area networks and PABXs for data communications, the integration of foice and data, evaluating PABX facilities and future developments in PABX technology. PABXs are currently available in three basic designs. Electromechanical switching is the oldest and, in terms of capital cost, the
vol 5 no 3 june 1982
cheapest, while common-control crossbar switching and stored programme control (SPC) operate with either analogue or digital switching. The SPC PABXs offer the greatest range of facilities (threeparty calls, camp-on-busy, extension renumbering in software etc.), but have always been more expensive in terms of capital cost than crossbar or electromechanical designs. Although SPC machines should be cheaper to maintain, British Telecom's policy of charging more for such maintenance has mitigated against this. The British Telecom Act should help, however, since by 1983, British Telecom's
unpredictable impact. Hardware expenditures associated with such services will show a similar increase, with an expected threefold increase in multiplexer installations over the next five years. A comparable gain will occur for local on-site networks, as well as a substantial increase in networkswitching node controllers. However, only a modest increase in the number of cluster controllers and communications controllers will take place over the period. These forecasts are based on a survey that asked users to project budgets. The survey also suggests that dedicated private lines, together with the dial-up network, will carry more than 80% of all data traffic; private networks will carry another 14%; and packet-switched public data networks (value added networks) about 3%. Terminal data speed will continue to rise, with 33% of the respondents reporting line rate usage at I 200 to 4 800 bit/s. Also, the critical priority among users when selecting a data communications service is its reliability and availability, the report finds, followed by cost and response time. (Frost & Sullivan Inc., 106 Fulton Street, New York, NY 10038, USA. Tel: 212 233 1080) []
maintenance monopoly, at least for SPC PABXs with digital switch matrices, will be removed. A chapter is dedicated to the issues raised by the recent changes in UK regulations. The report concludes that while there is unlikely to be any revolutionary change in the next eighteen months, the onus will be increasingly on the user to choose the right system. The exchanges supplied by British Telecom, GEC-Reliance, IBM, IIT, Philips, Plessey and Thorn-Ericsson are described in detail, with features and facilities tabulated for comparison between all the currently available models. (Communication Studies and Planning Ltd., Circus House, 21 Great Titchfield Street, London WI P 7FD, UK. Tel: 01 580 5271, Tx: 291216) []
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FCC, scheduled to come into operation before the mid 1980s, • three value-added networks, introduced in the mid 1970s, aimed directly at data processing applications and performing operations on information transmitted, including formatting, speed, code and protocol conversion, • a range of message service offerings, including Western Union Mailgram, Tymnet-Tymegram and FTE/Telenet-Telemail; the new electronic mail services, such as Tymnet-Ontyme; and sophisticated facsimile services that provide code, speed and format conversion between incompatible terminals, such as Graphnet and ITT/DTS-Faxpak services. All such services will gain importance in the future, the report says. In addition, it expects videotext/ teletext developments to have an
P A B X s - the user guide Communications Studies and Planning, UK (1982) 200 pp, £185 This report contains a full user specification of all the PABXs currently approved by British Telecom for connection in the UK. The guide also covers the design of private telephone networks, dimensioning an exchange, implementation and maintenance, the choice between the use of local area networks and PABXs for data communications, the integration of foice and data, evaluating PABX facilities and future developments in PABX technology. PABXs are currently available in three basic designs. Electromechanical switching is the oldest and, in terms of capital cost, the
vol 5 no 3 june 1982
cheapest, while common-control crossbar switching and stored programme control (SPC) operate with either analogue or digital switching. The SPC PABXs offer the greatest range of facilities (threeparty calls, camp-on-busy, extension renumbering in software etc.), but have always been more expensive in terms of capital cost than crossbar or electromechanical designs. Although SPC machines should be cheaper to maintain, British Telecom's policy of charging more for such maintenance has mitigated against this. The British Telecom Act should help, however, since by 1983, British Telecom's
unpredictable impact. Hardware expenditures associated with such services will show a similar increase, with an expected threefold increase in multiplexer installations over the next five years. A comparable gain will occur for local on-site networks, as well as a substantial increase in networkswitching node controllers. However, only a modest increase in the number of cluster controllers and communications controllers will take place over the period. These forecasts are based on a survey that asked users to project budgets. The survey also suggests that dedicated private lines, together with the dial-up network, will carry more than 80% of all data traffic; private networks will carry another 14%; and packet-switched public data networks (value added networks) about 3%. Terminal data speed will continue to rise, with 33% of the respondents reporting line rate usage at I 200 to 4 800 bit/s. Also, the critical priority among users when selecting a data communications service is its reliability and availability, the report finds, followed by cost and response time. (Frost & Sullivan Inc., 106 Fulton Street, New York, NY 10038, USA. Tel: 212 233 1080) []
maintenance monopoly, at least for SPC PABXs with digital switch matrices, will be removed. A chapter is dedicated to the issues raised by the recent changes in UK regulations. The report concludes that while there is unlikely to be any revolutionary change in the next eighteen months, the onus will be increasingly on the user to choose the right system. The exchanges supplied by British Telecom, GEC-Reliance, IBM, IIT, Philips, Plessey and Thorn-Ericsson are described in detail, with features and facilities tabulated for comparison between all the currently available models. (Communication Studies and Planning Ltd., Circus House, 21 Great Titchfield Street, London WI P 7FD, UK. Tel: 01 580 5271, Tx: 291216) []
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