Dial-up remote service

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Self-dialing remote service ( SWFD ) was a designation of the German Federal Post Office for the independent establishment of telephone connections by the caller to destinations outside the local network . The term has not been used since the digitalization of the telephone network, i.e. with the introduction of ISDN .

history

The first telephone exchanges were purely manual exchanges . A "lady from the office" had to be involved in establishing a conversation . The ever increasing volume of calls required a partial automation of the switching process, in which the caller can dial the number himself . From 1908 the self-dialing service was first implemented in local network traffic. As early as 1923 there were efforts to use automatic dialing for long-distance calls . The technology used only allowed long-distance calls to be made within a range of no more than 100 km. Only with the development of the EMD voter was there a switching device that made it possible to reach every participant within Germany with self- selection . Before the introduction of the self-dialing remote service, long-distance calls were only made using manual switching. The self-dialing remote service made it possible, from 1972 onwards, to automatically establish calls in long-distance traffic. With the introduction of the SWFD, participants were able to dial connections to participants who are in other local networks by dialing the number consisting of the local area code and participant number .

Network construction

Schematic network plan of the SWFD.

For the self-dialing remote service, the analog telephone network with the hierarchical network structure of the long-distance exchanges was divided into central exchanges (ZVSt), main exchanges (HVSt) and node exchanges (KVSt). Each exchange was the telephone traffic hub of its area. A complete mesh network existed between the central exchanges ; H. each of the eight ZVSt was connected to each other by long-distance lines. The central switching center was identified by the first digit of the telephone number (e.g. 6 for the central switching area Frankfurt am Main). The ZVSt areas were mostly divided into ten HVSt areas. The first two digits of the phone number identified the main exchange (e.g. 63 for the main exchange in Kaiserslautern), which were connected to the responsible ZVSt in a star shape. Each HVSt was also the node for the node exchanges connected to it in a star shape, and this in turn was the node for the end exchanges (local exchanges) to which the subscriber terminals were connected.

Individual evidence

  1. ↑ a b c Basics for Telecommunications Technicians, Heinz Körber, Fachbuchverlag Dr. Pfanneberg & Co, 1965
  2. ^ Manual for self-dialing long-distance traffic, Martin Hebel, Franckh'sche Verlagsbuchhandlung Stuttgart, 1962
  3. ↑ Handbook of Telecommunications Technology, Basic Series, Volume 8, Basics of Switching Technology, 6th edition, 1980
  4. ↑ Handbook of Telecommunications Technology, Book Series AFt Volume C5, Dialing Switching Technology, 5th Edition, 1970