SU849533A1 - Device for limiting initial telephonic calls - Google Patents

Description

The invention relates to telecommunications and can be used to restrict outgoing telephone calls. . A device for limiting outgoing telephone calls is known, comprising a line state sensor connected in parallel with the wires of the telephone line, two time delay units and a counter whose output is connected to the input of the decoder l. However, the known device does not allow to exclude connections of non-priority subscribers. The purpose of the invention is to exclude non-priority subscribers. In the device for limiting outgoing telephone calls, containing a line state sensor, connected parallel to the telephone line wires, two time delay blocks and a counter, the output of which is connected to the input of the decoder, a prohibition block, a program block and an executive block are entered. the output of the inhibit unit is connected to the input of a line state sensor, the output of which is connected to the inputs of the first and second delay units, with the output of the first delay unit and the output of the second delay unit; connection, respectively, to the first and second inputs of the counter; the output of the program block is connected to an additional input of the decoder, the output of which is connected to the control input of the execution unit, connected in series to one of the telephone line wires. The drawing shows a structural electrical circuit of the proposed device. The device contains a prohibition block 1, a line state sensor 2, the first and second blocks 3 and 4 delays counter 5, execute jfibHbrii block 6, decoder 7, programm block 8.

The outgoing telephone call restriction device operates in the following manner.

Before removing the handset, the device is in the initial state, while the high potential of the line state sensor (power supply voltage of the telephone line) arrives at sensor 2 of the line condition. From the line state sensor 2, a strictly defined potential arrives at the second delay unit 4, which reacts to it, while the unit 4 keeps the counter 5 at the installation input in the initial state.

After picking up the tube, sensor 2 of the line supplies a zero potential to delay blocks 3 and 4, while the second delay block 4 removes the inhibit signal from counter 5, and the first time delay block 3, which reacts to zero potential, returns to a working state.

When dialing a number, the dial pulses from the sensor 2 output of the line arrive at the input of the first delay block 3, which comes to its initial state. When the first dial pulse arrives. The time lag of block 3 is chosen such that when dialing any digit it is in the waste state, and during the inter-serial pause it is triggered. Thus, during the dialing of any digit, the first delay block 3 generates only one pulse, which starts Counter 5 and takes it one step.

The time delay of the second delay unit 4 is selected so that the high potential coming from the line state sensor 2 during dialing cannot put the second delay unit 4 into the working state and reset the counter 5 to the initial state.

 When a specified number of pulses arrive at the counter 5, a signal is generated at the output of the decoder 7, according to which the execution unit 6 triggers, breaking the telephone circuit with its contacts. Further formation of the dialing pulses is completely excluded, as the station is disconnected.

At the output of the sensor 2 of the line state, a potential appears, which is fed to the input of the second unit 4

delays, the time delay of which is chosen such that after disconnecting the telephone apparatus, the station is disconnected. After this time has elapsed, unit 4 is triggered and the counter 5 returns to its initial state, which in turn, via decoder 7, removes the control signal from the executive unit 6, connecting the telephone set with its contacts.

A readiness signal appears in the handset;

Thus, dialing non-priority numbers does not occur. The device can be connected at any point of the monitored telephone line and not load it. In addition, the device can be quickly reconfigured to any number of characters in the number, as well as block or allow its operation, eliminates false positives.

Claims (1)

1. USSR author's certificate No. 620027, cl. H 04 M 3/38, 1976 (prototype).