KR920001685B1 - Multi frequency sending/receiving method - Google Patents

Abstract

The method sends multi-frequency digit signal toward the digit input by a subscriber of a private branch exchange. The method comprises: (A) checking that startionary line selection digit is received; (B) designating public telephone line and assigning channel when the stationary line selection digit is input; (C) checking that the station subscriber phone number digit is input when the stationary line selection digit is already input; (D) checking the first and the last digit input; (E) cancelling the pre-assigned time slot and sending MF digit signal for the first digit; (F) re-assigning a time slot after sending the MF digit signal for the last digit; and (G) sending the MF digit signal for the intermediate digits.

Description

Multi-frequency digit extraction method

1 is a schematic diagram of a private exchange.

2 is a flow chart of the present invention.

* Explanation of symbols for main parts of the drawings

100: trunk circuit 200: CPU

300: subscriber circuit 400: switching circuit

The present invention relates to a method for transmitting a multi-frequency digit to a private exchange in a private exchange.

In general, a private exchange is a device for providing a voice call service between a subscriber and an extension subscriber or between subscribers.

The private exchange includes a trunk circuit for relaying the local exchange and the private exchange, and the trunk circuit includes an MFS (Multi-Frequency Sender) and a MFR (Multi-Frequency Reciver) for transmitting or receiving a multi-frequency digit. Withdraws MF digits (Multi-Frequency Digit) when a call is requested with a domestic subscriber

The trunk circuit is configured as 100 in FIG. 1 and the operation of MF digit transmission is described as follows. When data is drawn from the central processing unit (hereinafter referred to as CPU) 200 through the line L5, the MFS 107 outputs a multi-frequency digit signal to the filter 102 through the line L3.

The timeslot assignment and decoding circuit 108 also assigns timeslots to the CVSD 101 by digits on the line L5. In this case, the CVSD 101 converts an input signal input to the line L4 into a digital signal and outputs the switching circuit 400 through the transmission highway (hereinafter referred to as SHWX) L1 or receives the reception highway from the switching circuit 400. The digital signal inputted through (hereinafter, SHWR) L2 is modulated and transmitted through the line L3.

That is, the CVSD 101 is assigned a time slot before the MFS 107 transmits an MF digit signal. The time to be allocated is assigned from the moment when one of the public telephone communication networks is turned on. The reason is that the time slot must be allocated as described above so that the subscriber can hear the dial tone and the subscriber will send a digit.

Therefore, the MFS 107 transmits the MF digit signal through the line L3 while the timeslot is assigned to the CVSD 101, and the filter 102 transmits the MF digit signal through the SHWR L2 and the CVSD 101. There is a problem that is disturbed by the signal to be drawn out.

Accordingly, an object of the present invention is to provide a multi-frequency digit retrieval method capable of accurately transmitting an MF digit signal for a digit input by an extension subscriber in a private exchange.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a flow chart of the present invention, in which a first process for checking whether a CO line selection designation digit has already been inserted from an extension subscriber and a CO line selection designation digit for entering if a CO line selection designation digit has not already been entered in the first process. A second process of designating a public telephone line and assigning a call channel on a CO line, and a third process of checking whether a digit for a CO line subscriber number is entered if a digit for CO line selection designation has already been entered in the first process; A fourth step of checking whether the first digit or the last digit is input when the digit is inserted in the third step, and a fifth step of canceling the allocated time slot and transmitting an MF digit signal when the first digit is the fourth digit. And a sixth process of reassigning a time slot after transmitting an MF digit signal in the case of the last digit in the fourth process; In the fourth process, if it is not the first and last digits, a seventh process of transmitting an MF digit signal is performed.

Therefore, the present invention will be described in detail with reference to FIG. 2 and FIG. When a subscriber of a private exchange wishes to be served by a national exchange, he must select one of several public telephone lines. Then let's explain with an example.

If the subscriber wants to catch the Seoul CO line in the present Giheung, he / she will dial the CO. (Usually “9” here) If there is an empty public telephone turn, the relay RL1 is turned on to form a current loop with the trunk line switch. The local exchange detects this and plays the dial tone. In this case, the private exchange can only hear the time slot.

The subscriber then dials the desired telephone number the same as calling from Seoul. However, since it is not possible to receive this directly from the national exchange, the subscriber sends a digit one by one through the MFS 107.

After this, the national exchange finds the subscriber and if the subscriber is idle, the ringback tone is audible when the subscriber is busy. Of course, again, the private exchange must be assigned a timeslot.

Therefore, it is impossible to handle such a thing in the current hardware structure. Therefore, we have no choice but to let the software take care of this.

2 is performed by the CPU 200 of FIG. 1, which will be described below. The CPU 200 checks whether a digit for selecting a CO line selection (for example, "9") has already been input from the extension telephone set (STN) through the subscriber circuit 300 (step 10).

This is to determine whether the subscriber is providing the public telephone line and the voice call service or the subscriber before providing the voice call service.

If the digit for the CO line selection designation is not input in step 10, the CPU 200 checks whether the digit for the CO line selection designation is input from the extension telephone (STN). If not, return to step 10.

When the trunk line selection designating digit is inserted in the eleventh step, the CPU 200 checks whether there is a public telephone line that is not in use through the transformer 109, the hook state detection unit 103, and the multiplexer 105. Step 12)

If there is a public telephone line that is not in use in the twelfth step, the CPU 200 drives the address abl 106 and the relay driver 104 to turn on the relay of the non-used public telephone line. The timeslot is allocated to the CVSD 101 through the timeslot assignment and decoding circuit 108 (step 13).

On the other hand, when the CO line selection designation digit is input in step 10, the CPU 200 checks whether the digit for the CO line subscriber is input from the extension telephone (STN).

If no digit is input at this time, the process returns to the tenth step. When the digit for the counterpart subscriber is input in step 14, the CPU 200 checks whether the input digit is the first digit of the desired CO line subscriber number.

In the fifteenth step, if it is the first digit, the CPU 200 transfers the time slot allocated to the CVSD 101 to at least the next (step 17) MFS 107 via the line L5. And the MFS 107 is sent to the public telephone line through the line L3, the filter 102 and the transformer 109. (Step 18).

If the first digit is not the first digit in the fifteenth step, the CPU 200 checks whether it is the last digit.

If it is not the last digit in the sixteenth step, the CPU 200 transmits the MF digit signal to the public telephone line in the same manner as in the eighteenth step.

In step 16, the CPU 200 transmits the last MF digit signal to the public telephone line (step 20), and then waits for about 100 ms (step 21). This is because if the bit timeslot is allocated after the data is applied to the MFS 101, the same problem occurs in the last MF digit signal. To give 100ms is enough time delay to detect the MF digit signal in the local exchange as 60ms-100ms.

After waiting for a predetermined time, the CPU 200 allocates a timeslot to the CVSD 101 again (Step 22).

In this way, depending on the status of the subscriber to be found at the local exchange, the ringback tone or the ring tone can be heard. And the detailed description of the operation of Fig. 1 was weak because Fig. 1 is widely known as the private exchanger circuit currently in use.

As described above, the present invention has an advantage in that when the MF digit signal is sent, the MF digit signal is not affected by an external signal so that the correct digit can be sent.

Claims (1)

In the MF digit withdrawal method of a private exchange, a first step of checking whether a CO line selection designation digit has already been entered from an internal subscriber, and if a CO line selection designation digit has not already been entered in the first step, A second process of designating a public telephone line and assigning a call channel on the incoming line; and a third process of checking whether a digit for the CO line subscriber number is entered if the digit for selecting the CO line is already entered in the first process. And a fourth step of checking whether the first digit or the last digit is input when the digit is inserted in the third step, and a fifth step of canceling the allocated time slot and transmitting an MF digit signal when the first digit is used in the fourth step. And reassigning a time slot after transmitting the MF digit signal in the case of the last digit in the fourth step. And a seventh process of transmitting an MF digit signal if the first and last digits are not the fourth digit in the fourth process.

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