Mạng và viễn thông P22

Electronic Mail, Znternet and Electronic Message ServicesThe ability to connect two computers together and, with relative ease, to send information from one to the other, is bringing a revolution in the way in which business and life as a whole is conducted. Today it is possible to run your bank account from home, book your holiday, send electronic messages to your work colleagues or friends, and look up to see what is on at the theatre in London orNew York City.Alternatively companies may make their orders to and pay their bills from their suppliersby computer program and‘electronic data interchange’....
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Mạng và viễn thông P22 Networks and Telecommunications: Design and Operation, Second Edition. Martin P. Clark Copyright © 1991, 1997 John Wiley & Sons Ltd ISBNs: 0-471-97346-7 (Hardback); 0-470-84158-3 (Electronic) 22 Electronic Mail, Znternet and Electronic Message Services The ability to connect two computers together and, with relative ease, to send information from one to the other, is bringing a revolution in the way in which business and life as a whole is conducted. Today it is possible to run your bank account from home, book your holiday, send electronic messages to your work colleagues or friends, and look up to see what is on at the theatre in London orNew York City.Alternatively companies may make their orders to and pay their bills from their suppliersby computer program and‘electronic data interchange’. A number of technologies enabled revolution: have this videotext, electronic electronic mail, data interchange (EDI) and Internet. We review the telecommunication aspects of these technologies in this chapter.22.1 VIDEOTEXT Videotext was the first type of device specially designed to allow telephone network customers to use a cheap device to access information from a large public database. The original technology and standards, including special terminals and modem techniques allowing asymmetric transmission (a high bitrate channel for information download to the customer with a low speed control channel for his ordering of different pages of information) have now been overtaken by modern personal computer based technology, but the appearance of the worldwide Internet has stimulated recent rapid growth for the long established videotext service providers (British Telecom’s Prestel, Deutsche Telekom’s Bildschirmtext, BtX or Datex-J, and France Telecom’s Minitel). The idea of videotext is that, using a low cost terminal in the form of a small tele- vision, a customer can make a phonecall to a public central database, where he could access all sorts of pages of information which he could then have displayed on his screen. Thus, for example, he might access tomorrow’s weather forecast, current flight arrival information, information about financial markets, about holiday offers, about dating services or, via an extended connection to the railway company or his bank, might even order a train ticket or pay his bills. 399400 ELECTRONIC INTERNET MAIL, AND ELECTRONIC MESSAGE SERVICES Videotextinitsoriginal form in theUnitedKingdom(as Prestel) was quickly accepted by the travel industry, which used it widely as a means for holiday companies to advise travel agents of available itineraries and to book tickets on behalf of clients. It came at a time of revolutionary computerization of the airline industry in particular, when simultaneously the airlines were cooperating to establish and operate common and inter-linked computer ticket and booking systems. In France, videotext became the standard method for telephone directory enquiries. The Minitel terminals were given away free by France Telecom. They justified doing this initially by the cost savings brought about by fewer telephone enquiries to human operators, but nowadays they also make money from the telephone calls which cus- tomers are making to the other information services which have subsequently sprung up. Some services, including the pink pages of dating services, are world renowned. In Germany, the Deutsche Telekom’s(formerlyDeutscheBundespost’s) T-Online service (the new name for the modern version of Bildschirmtext, Btx or Datex-J) had been a commercial non-runner for years. Suddenly, however, during 1995 demand for connections started to increase rapidly. The reason was the cheap availability of access to the Internet using standard personal computers. It is the Intern ...