Network group Weilheim
The network group Weilheim was in 1923 the first telephone network with IDD in the world. It included the city of Weilheim in Upper Bavaria and most of the surrounding towns within a radius of approx. 25 km. This network made it possible for the first time to dial telephone connections in long-distance traffic, i.e. between telephone subscribers from different local networks .
Original network structure and working method
Each number was only assigned once in the entire network. It was therefore sufficient to simply dial the desired number from any network connection without the area code . It was not necessary to know in which place the desired interlocutor lived.
However, for technical reasons, the number blocks were sorted geographically. The first up to four digits of a phone number thus stand for belonging to a specific local area network. It was therefore a hidden numbering . Until a few years ago, phone numbers were still distributed in German cities according to this model: The phone numbers within a city district usually began with the same combination of digits. The possibility of transferring phone numbers after moving within the local network or after changing provider is increasingly blurring this spatial allocation.
The last two digits denote the desired subscriber connection within the local network. For most places this capacity of a maximum of 100 participants was initially sufficient. Only the larger towns were assigned several hundred number blocks.
The Weilheim network group, which initially comprised 22 local networks, was tree-shaped (almost star-shaped) with these three levels:
- the main office in Weilheim as the center of the entire network,
- five other connected node offices in Dießen , Peißenberg , Schongau , Murnau and Kochel ,
- 22 terminal offices connected to this in a star shape , each forming the transition to a local network.
The node office in Peißenberg also served as a transit point from Weilheim to the more distant node office in Schongau. All other node offices were connected to the main office in a star shape via direct lines.
By picking up the receiver, the request for a conversation was forwarded directly to the main office in Weilheim. The first digits dialed then stipulated which node and end office the call was to be forwarded to, until the last digits were finally used to select the desired subscriber within the destination local area network.
A fundamental problem was that every call initially occupied an expensive long-distance line to the main office, even if it was only a local call, because this distinction could often only be made after several digits had been dialed. To mitigate this effect, the first digits dialed were also evaluated in the outgoing local network in parallel to the main office. If they matched their own local area code, a reversing dialer initiated the direct on-site transfer and immediate release of the trunk line. This enabled the blind occupancy of long- distance lines to be limited to a few seconds per call.
Billing
Another problem in principle was billing. Long-distance calls were billed in indivisible units of three minutes at the beginning of each section of three minutes (in today's common notation, clocking 180 / 180). For distances over 100 km, the fee was due for the first three minutes at the beginning of the call and then at the beginning of each minute a third of the three-minute fee (in today's common notation, clocking 180/60). In the Weilheim network group, the 180/180 cycle was used due to the distances between the local networks.
In the first time after the opening of the Weilheim network, every connection was interrupted after three minutes. Should the connection be continued, the calling subscriber had to dial number 1. In doing so, he switched the charge meter on and re-established the connection for three minutes. This operating mode was changed with the introduction of further developed so-called time zone counters. They counted automatically and alerted the participants with an acoustic signal shortly before the end of a three-minute segment that a new three-minute fee would soon be due. The participants then had the opportunity to end the conversation.
In the hand-switched long-distance service, participants could alert the operator immediately after the connection was established that they were connected incorrectly. If the operator made the wrong transfer, although the subscriber had been confirmed with the correct number when registering, no charge was due for this incorrect connection. An operator did not participate in the self-dialing remote service and the calling subscriber could only have applied after incorrect connections not to collect the fee for a three-minute call already due with the notification of the called subscriber; but he would have had to prove that he had chosen correctly and was still connected incorrectly. In order not to burden the subscriber with the full charge for a three-minute call in the event of a wrong dialing, the further developed time zone counters observed a waiting period of 5 seconds, later 10 seconds, from the notification of the called subscriber. If the calling subscriber hung up again during this time, the call was only counted as a local call. The waiting period was long enough for the calling party to be able to inform the called subscriber that he was wrongly connected with the recommendation at the time: "Error, please attach!"
The time zone counters saved the charges accruing during the call and only transmitted the associated counting pulses to the call counter of the calling subscriber after the call had ended. The time zone counters could store 60 charge units. This storage capacity resulted in a limitation of the call duration to 6 or 12 minutes, depending on the distance, before the memory of the time zone counter was full. The time zone counter then alerted the participants with an acoustic signal that the connection was imminent. If the participants did not terminate the connection in response to the signal tone, the time zone counter forcibly disconnected them. The participants were able to dial the connection again immediately. This type of billing was only replaced in 1948 by counting during the call, which made connections of unlimited length possible.
Introduction of the open key figures
As recently as 1926, the use of hidden key figures was seen as the preferred form of operation in direct dial-up remote service, also because it made fewer demands on the subscriber. It turned out, however, that the disadvantages of the hidden key figures predominated. In particular, the self-dialing remote service between different network groups could hardly be implemented without open codes and the hidden codes made the phone numbers unnecessary, even for local calls. The Weilheim network group was therefore converted to open numbering . In 1929 real (open) local area codes were introduced in this network for the first time. In order to set up a long-distance call, the traffic elimination number 0 first had to be dialed, followed by further digits that indicated the destination network. All dialed numbers that did not begin with a 0 stood for a local call that - in contrast to the previous hidden code system - could be made directly within the locality without using the long-distance network.
The basic network structure with the main, node and end offices mentioned was retained. The local network codes were also provisionally planned in such a way that they could be assigned several times in several non-neighboring network groups and that the local network codes could differ depending on the origin of a self-dialing long-distance connection. A nationwide uniform plan for general area codes was only introduced after the Second World War.
Integration into the German state telephone network
The successful three-tier star structure and the principle of open key figures formed the model for the long-distance dialing system Technik 62 (T 62), which was introduced nationwide in 1962 . Together with the newly introduced central offices in eight central cities in what was then the Federal Republic of Germany, including West Berlin, there were four hierarchical levels, central, main, node and end office, into which the main office in Weilheim and its sub-structures could be easily integrated.
With the integration of the Weilheim network group into the federal German state long-distance dialing network, changes in the numbering plan were inevitably accompanied by changes in the numbering plan, although some of the earlier digit assignments can still be seen in the area codes that are valid today. In particular, the gaps in digits that still exist today in the area of the switching centers in Murnau (088-41, then the gap from -42 to -44, continue with -45), Kochel and Schongau go back to the old numbering plan with the number blocks of hundreds.
The knot offices in Dießen and Peißenberg were dissolved. On the other hand, the newly established node office in Garmisch-Partenkirchen was connected to the main office in Weilheim, so that from then on Weilheim served four open node offices.
Since then there have been no more area code changes in the 088xx numbering range.
The numbering plans in direct comparison
The numbering plan is 1. sorted by digits and 2. structured according to node office areas. The 0 (zero) is sorted after the 9 according to its position on the dial . Place names in bold denote the seat of a main office or node office.
| Number blocks (hidden codes) from 1923 | Open key figures from 1929 | Area codes in the national long-distance dialing network from 1962 |
|---|---|---|
| 2 xx - 5 xx Weilheim | 08 1 Weilheim
08 2 Huglfing |
088 1 Weilheim
088 01 Seeshaupt |
|
74 xx - 77 xx Dießen
704 xx- 708 xx Utting |
088 21 Garmisch-Partenkirchen
088 22 Oberammergau |
|
|
81 xx Wessobrunn |
||
|
841 xx - 844 xx Murnau
845 xx Kohlgrub |
08 4 Murnau (initial digits 2 to 4)
08 45 Bad Kohlgrub |
088 41 Murnau
088 45 Bad Kohlgrub |
| 803 xx - 806 xx Peissenberg | 08 5 Kochel (first digits 2 and 3)
08 56 Penzberg |
088 51 Kochel
088 56 Penzberg |
|
8071 xx - 8073 xx Schongau
8075 xx Rottenbuch |
08 6 Schongau (initial digits 2 to 6)
08 61 Steingaden |
088 61 Schongau 088 62 Steingaden |
|
91 xx - 94 xx Kochel
95 xxx Penzberg |
08 7 Dießen (initial digits 2 to 4)
08 77 Utting |
|
| 08 0 Peißenberg (initial digits 7 and 8)
08 09 Hohenpeissenberg |
literature
- Joachim Heberlein: Weilheim as a cosmopolitan city of telecommunications. In: Weilheimer Tagblatt , weekend edition from 17./18. May 2008, Local, page 9; Full-page article on the Saturday side of the issue
Web links
Individual evidence
- ^ Martin Hebel: Handbook for self-dialing long-distance traffic, Franckh'sche Verlagshandlung Stuttgart, 1962, p. 29
- ↑ a b c d e Martin Hebel: The model of the network group Schaftlach at the German traffic exhibition in Munich as a vision of the future of German telephony. In: Journal for Telecommunications, Werk- und Gerätebau (Journal of the Association of German Low-Power Industrialists) 1926, pp. 1–14, 22–26 and 39–43
- ↑ a b z. B. Official telephone book for the district of the Reichspostdirektion Nuremberg 1938, p. 6, section self-dialing remote service
- ↑ z. B. Official telephone directory for the Munich local network 1951, here the local networks that can be reached in the self-dialing service are already subdivided according to networks with counting during the call and after the call
- ↑ a b Erich Müller-Mees: The self-dialing remote service at the German Reichspost. In: Der Europäische Fernsprechdienst 1942 , p. 29 ff.
- ↑ Lecture documents on basic functions of telephone switching technology, part 2 by Hans Thomas, September 2003 edition, Fig. 1–2 ( Memento of the original from September 28, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ W. Clausen: The self-dialing remote service and its effect on the user with special consideration of the experiences in the Rhenish-Westphalian industrial area. In: Journal for the electrical telecommunications system , 1953, p. 124 ff.
- ^ A b Rudolf Führer: Landesfernwahl, Volume 1, Verlag R. Oldenbourg, Munich / Vienna 1966
- ↑ Official directory of the area code (AVON) of the Deutsche Bundespost (issues 1966 to 1992) and directory of the area codes and tariff areas of Deutsche Telekom (issue 1996)
