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Paging Systems It is often important to be able to reach certain people very quickly. The conventional telephone network is not always optimal, because a line may be engaged or the person being called might not be available. Mobile telephone systems offer a high degree of reachability of a mobile subscriber, but MSs are not always switched on and are expensive to use. Paging systems fill a particular gap (see Table ). They allow unidirectional transmission of information in the form of a tone or a numeric or alphanumeric message to the person being contacted, whose location area is not known. | Mobile Radio Networks Networking and Protocols. Bernhard H. Walke Copyright 1999 John Wiley Sons Ltd ISBNs 0-471-97595-8 Hardback 0-470-84193-1 Electronic 7 Paging Systems It is often important to be able to reach certain people very quickly. The conventional telephone network is not always optimal because a line may be engaged or the person being called might not be available. Mobile telephone systems offer a high degree of reachability of a mobile subscriber but MSs are not always switched on and are expensive to use. Paging systems fill a particular gap see Table . They allow unidirectional transmission of information in the form of a tone or a numeric or alphanumeric message to the person being contacted whose location area is not known see Table . A terminal is required that is constantly ready to receive but cannot transmit and consequently is small lightweight and inexpensive. A paging message is automatically initiated when a telephone user dials the paging service and using a telephone keyboard an Internet terminal or a PC conveys the pager number of the called person or a short message for it to the computer that responds see Figure . One characteristic of the paging system is that the person sending the message can never be certain that it has been received. There can also be a considerable gap between the time a message has been sent and when it is received by the addressee and during peak load times this can amount to 10 minutes. Table Public operation of paging systems in Europe Since 1974 Since 1989 Since 1990 Since 1996 European Paging Service Eurosignal Cityruf Euromessage ERMES Table Call types of different paging systems Call type Eurosignal Cityruf ERMES Tone only No. of paging no. Up to 4 Up to 4 Up to 8 Numeric No. of num. char. Up to 15 20-16 000 Alphanumeric No. of char. Up to 80 400-9000 Transparent data transm. max. length 4000 bits 440 7 Paging Systems Call Centre DTMF Dialing Networks like - Telephone - Telex - ISDN -

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