Device for decentralized call forwarding
The device for decentralized call forwarding ( GEDAN ) was an additional device in the switching system of the former analog telephone network of the Deutsche Bundespost . It made it possible for every subscriber to have incoming calls automatically forwarded to another telephone connection of his own choosing . GEDAN was the first implementation in the German telephone network of today's standard call forwarding immediately (CFU).
history
After a field test with its predecessor CADI ( Call Diverter ), GEDAN was introduced nationwide in 1983. At the end of 1984 there was a conversion to the "GEDAN 2" version, with new performance features and improvements that responded to objections from participants. In 1983 the development of "GEDAN 3" began. Another version "GEDAN 4" followed.
functionality
The task of GEDAN was to forward a call to any other telephone connection than the telephone connection dialed by the caller. GEDAN had to be commissioned and paid for by the customer who wanted to use call forwarding. The GEDAN customer received in addition to his actual phone number (in the figure the "1st exchange line") an additional exchange line whose phone number was hidden (in the figure the "2nd exchange line"). The GEDAN was installed in the local exchange . The GEDAN customer's basic equipment included the conventional analog telephone connection with a special telephone. The forwarding was either set up permanently or could be activated or deactivated by the GEDAN customer as required. When forwarding was activated (situation shown in the illustration), all incoming calls were forwarded to the forwarding destination, the GEDAN customer's phone did not ring. The caller first heard an announcement that his call would be forwarded: Hello, call forwarder here. Your call will be forwarded . The caller incurred no additional costs for forwarding the call. The connection fees incurred for the connection from GEDAN to the diversion destination were borne by the GEDAN customer. The GEDAN customer could still make outgoing calls with activated call forwarding, unless a forwarded phone call was taking place. If the GEDAN customer picked up the receiver while a diversion was in progress, they received a corresponding announcement. With the forwarding deactivated, the GEDAN customer could use his telephone connection normally.
Operating modes
Call forwarding was available in different operating modes:
- Fixed forwarding, always active ( operating mode 1 ): The GEDAN customer had a phone number, but did not need a telephone connection and therefore no telephone. If the number was called, the programmed forwarding destination was always reached.
- Fixed diversion, activated individually ( mode 2 ): The GEDAN customer had a phone number and a telephone connection with a special telephone. Although the forwarding destination was programmed, the GEDAN customer was able to determine whether calls would reach him directly (GEDAN deactivated) or be forwarded (GEDAN activated) by entering a key on his telephone.
- Free choice of forwarding destination ( mode 3 ): As mode 2 , but the GEDAN customer can also program the call number of the forwarding destination himself.
- Operating mode 4 : As operating mode 3 , however, as with operating mode 1 , the GEDAN customer does not need a telephone connection.
Up to "GEDAN 2" only operating modes 1 to 3 were available, from "GEDAN 3" there was also operating mode 4 .
technology
GEDAN had a modular structure and consisted of a subrack and various electronic assemblies . The subrack was equipped with central assemblies for power supply and announcement, as well as with up to five GEDAN units, each consisting of a "call forwarder" and "amplifier". The amplifier had an automatic gain adjustment to increase the volume in the case of remote connections in order to comply with the specifications of the attenuation plan of the telephone network. In GEDAN versions 1 and 2, however, the amplification was message-controlled; H. it was only amplified in the direction of the currently speaking participant to the other participant; the opposite direction was heavily dampened. This meant that instead of the two-way communication that is common when making calls, only two-way communication was possible.
programming
The GEDAN could be activated and programmed in different ways:
- Programming by a technician from the Deutsche Bundespost with the so-called "input device" directly on the "call forwarder" assembly. Only this programming method was possible in operating mode 1.
- Self-programming by the GEDAN customer
Examples of programming:
- Enter the call number of the forwarding destination: *BLift the #handset Enter the call number Hang up the handset
- Activating call forwarding: lift the *A#handset and replace the handset
- Deactivating call forwarding: Lift the handset and replace the *D#handset
Terminals
Since the connection line for the GEDAN customer was a conventional telephone connection, all analog devices of the time were in principle suitable for telephoning. But were for the activation and programming, the modifier keys A, B, Cand Drequired so that suitably equipped phones were used for. B. " FeAp 80" or "FeAp 76".
Alternatively, a GEDAN programming transmitter was used.
literature
- Instruction sheets of the German Federal Post Office Issue B telecommunications
- 37th volume, edition 9/1984
- 38th volume, issue 2/1985
- 40th year, issue 1/1987
- Teaching sheets of the Deutsche Bundespost TELEKOM, 43rd year, edition 5/1990
Web links
Individual evidence
- ↑ a b c Device for decentralized call forwarding GEDAN : instruction sheets of the German Federal Post Office, issue B Telecommunications, 9/1984, p. 317
- ↑ a b Device for decentralized call forwarding GEDAN : instruction sheets of the German Federal Post Office, issue B Telecommunications, 2/1985, p. 53
- ↑ a b GEDAN 3 - call forwarding with new features : instruction sheets of the Deutsche Bundespost TELEKOM, 5/1990, p. 237
- ↑ Robert Schoblick, Dirk Gommolla: ISDN in practical use , Franzis' Munich 1992, ISBN 978-3-7723-4481-7
- ↑ Operating instructions GEDAN input device , Deutsche Bundespost, 06/1984
- ↑ Brief operating instructions for programming transmitters for call forwarding. Accessed March 31, 2020 .
