DE1035215B - Circuit arrangement for telephone dialing systems for the transmission of messages from the calling party to the called party in the event of a call not being made - Google Patents

Description

In telephony, facilities are known which enable messages from a calling party to be sent to the called party to give a ready-to-switch sound storage device if the called party does not answer the call, for example because of absenteeism queries. Such devices, one of which is perfectly executed under the name of Ipsophon is described ("Das Elektron", 1948, p. 166), have the prerequisite that the line to the called · Subscriber is free and the called subscriber does not answer. Because of their great technical effort such systems are very expensive and therefore have little prospect of being used in larger scope.

The invention is based on the consideration that in many cases it is sufficient to have an inaccessible Telephone subscribers to send the message from whom a connection with him is desired has been. It also sets itself the task of ensuring that this communication can also be canceled if the desired set is currently busy. This is particularly important for long-distance connections or if the partner has conversations very often and it is more a matter of chance, establish a connection with him to get. In a further development of the invention, it should be possible, except for the simple one Notification of who has called to transmit further messages in a form coded with digits and numbers.

The invention achieves this by the connection in the last voter level of the exchange facility a switching means on the busy signal of the called subscriber or after several alarm calls being prepared. This switching means switches to one depending on further dialing pulses the subscriber line lying switch to a signal frequency source. the frequency of the others Dialing pulses from the calling subscriber, his / her phone number or a message encoded by digits correspond, implemented and via an electrical switch to the called subscriber to and from there be fed to an evaluation device via a receiving splitter.

The idea of the invention and its further configuration are intended to be based on an exemplary embodiment Hand of the drawings are explained in more detail.

It is based on the known circuit of the dialing system 50 of the German Federal Post Office (See for example Fernmelde-Ingenieur, 1953, p. 25), of which only the essential current flows of the local long-distance line selector OFLW are shown. The additions required according to the invention are highlighted by a stronger representation in the drawing (Fig. 1). They consist of a transmission circuit arrangement

for telephone dialing systems for

Transmission of messages

from calling to called

if the conversation did not take place

Applicant:

South German telephone apparatus,

Kabel- und Drahtwerke A. G., TE Ka DE, Nuremberg, Allersberger Str. 185

Curt Eichler, Nuremberg,
has been named as the inventor

soft SW, which is looped in before the voter input of the last selection level, with the contacts s2 and s 3 of the relay 5 "shown separately in Fig. 7. Another contact j4 of the relay S is looped into the circuit of the voter magnets D and H. On the receiving side, a separating receiving switch EW with the evaluation device AG is provided at the subscriber between the subscriber set TIn and the line Ltg.

If an OFL voter equipped in this way is reached by the caller by dialing the code and is occupied via his c-wire, the last two dialing pulse series (end digits of the desired subscriber number) are sent to relay E, from where they are sent to the voter-lift-turn- Act with magnets H / D. In a known manner, the delayed relay V and the LTmschaltelais U are effective.

At the end of the election, the voter stands with his arms on the multiple contacts of the called subscriber with his / her arms still open (contact αΙ1Ιαϊϊ12). In the usual way, the test relay P is used to check whether it is free or occupied. In the first case, a dial tone is transmitted to the calling party and a callsign to the called subscriber in a known manner. Relays G and M take effect. In the other case, when the subscriber line is busy, the caller receives the busy signal again through relay G. If the OFLW and the called subscriber are provided with an arrangement according to the invention, an additional g-contact, not shown, gives the calling subscriber via the call and

809 579/127

Signal transmitter of the OFLW a special audible signal, similar to the busy signal, which means that he can continue dialing for the purpose of transmitting messages to the desired subscriber. at If the connection is free, this signal is only given after repeated unsuccessful alarm calls, d. h. when the called party does not report in a reasonable time.

If the calling subscriber dials further digits, e.g. B. correspond to its own number or another message content in coded form, the relay E is actuated in the OFLW by this pulse series, as in the normal choice. With the first impulse, an additional contact e9 closes the circuit of relay S prepared by contact g 3. Relay S is maintained via contact si until the selector is triggered and relay G drops out (g3). Via the closed contacts s2, s3 , controlled by the contact ei, a signal frequency SF passes in the rhythm of the dialing pulses via the transmission switch, the switch arms of the selector and from there via the line Ltg to the called subscriber. There, the signal frequency is branched off by appropriate filters in the receiving switch EW and fed to an evaluation device AG which, after rectification, records the pulses accurately as DC characters according to known methods. According to a further development of the invention, this recording can be carried out in a simple manner by a printing device which basically only consists of a number drum against which a paper strip, which is moved step by step by the pulses, is pressed against for the printing. The number drum is rotated by the impulses via a pawl and returned to the starting position by a return spring after each impression in the pauses between the impulse series. The digits appear one after the other at right angles to the movement on the tape.

A frequency above the voice frequency band, for example between 10 and 16 kHz, can be selected as the transmission frequency. This makes it possible to carry out the message transmission according to the invention even while the state is busy, that is to say during another call, and thus to use the telephone system twice. If the called subscriber ends another conversation while transmitting a message according to the invention and possibly establishes a new connection during this time, the transmission of the message is not disturbed because the occupied OFLW continues to be on the line of the called subscriber remains connected until the calling party hangs up. A contact j4 in the feed line of the lift-turn magnet HID prevents the rotary selector from moving ahead of time before the message transmission has ended. A contact s 5 can initiate the delivery of counting pulses to the calling subscriber from the time zone counting device ZZZ \ ^{r that has been} running with the message.

The arrangement can be simplified if the transmission of additional messages in the busy state is dispensed with. In this case, the charging frequency of 16 kHz, which is already available in the exchange, can be used as the signal frequency for the message transmission. At the subscriber, a switchover relay is to be provided after the charge switch, which switches the charge switch away from the evaluation device AG to the charge meter depending on the lifting of the subscriber set.

Claims (7)

Patent claims: 1. Circuit arrangement for telephone dialing systems for the transmission of messages from the calling party to the called party in the event of a failed conversation, characterized in that the connection of a switching means (S) is prepared in the last dial level of the exchange facility on the busy signal of the called subscriber or after several alarm calls ( Contact g · Z), which, depending on further dialing pulses (contacts9), switches on a signal frequency source (SF ) to a switch (SW) located on the subscriber line (contact s 2, s3) correspond to his call number or a message encoded by digits, implemented (contact ei) and sent to the called subscriber and that these pulses are fed to an evaluation device (AG) at the subscriber via a receiving switch (EW). 2. Circuit arrangement according to claim 1, characterized in that the calling subscriber a signal in response to the busy signal of the called subscriber or after several alarm calls receives as a request to transmit further messages in the form of dialing pulses. 3. Circuit arrangement according to claim 1, characterized in that the particular signal frequency above the voice frequency band, for example between 10 and 16 kHz. 4. Circuit arrangement according to claim 1, characterized in that the switch (SW) is looped into the α / fr cores to the subscriber in front of the selector of the last selection stage in such a way that the signal frequency reaches the called subscriber via a set selector. 5. Circuit arrangement according to claim 1, characterized in that a contact (si) of the switching means S prevents the rotary selector from continuing to run before the message transmission has ended. 6. Circuit arrangement according to claim 1, characterized in that a contact (s5) of the switching means (S) sends charge counting pulses to the calling subscriber during the transmission of the further messages. 7. Circuit arrangement according to claim 1, characterized in that the evaluation device when called subscriber only contains a pulse-controlled number drum against which to print a tape that is moved step-by-step with a pulse pause is pressed after each pulse series. 1 sheet of drawings © 809 579/127 7.58