JPH0595430A - Modem - Google Patents

Abstract

PURPOSE:To provide the MODEM which can be used easily even by a user who does not know a fact that even MODEMs conforming to CCITT V.25bis, some of them do not send out an answer tone signal. CONSTITUTION:The MODEM is provided with a deciding part for deciding whether an answer tone signal exists or not at every telephone number of the other party equipment, and a memory for storing a result of decision of the deciding part concerned, and executes automatically a dial-tone operation by switching a frequency of a detector to a carrier wave, when an answer tone signal by a dial-tone operation conforming to a CCITT(International Telegraph and Telephone Consultative Committee) V.25bis system is not detected within a prescribed time, or when the answer tone signal is not stored in the memory.

Description

Detailed Description of the Invention

[0001]

The present invention relates to CCITT (International Telegraph and Telephone Consultative Committee) V.V. The present invention relates to a public line modulator / demodulator compliant with 25 bis.

[0002]

2. Description of the Related Art CCITT V. The connection procedure at the time of a calling operation in the public line modulation / demodulation device conforming to 25 bis is shown in FIG.
It is shown like the flowchart of. CCITTV. Two
In the 5bis system, the response of the counterpart modulation / demodulation device is determined by the presence or absence of an answer tone signal (2100 Hz). 5
0 seconds, if the answer tone signal is not detected (step S _15), the other party in response to disconnect the line and determined not to be a modem (step S _16). Moreover, also disconnects the line when the other party of the line is in use (step S _12). If the answer tone is detected (step S _6, S ₁₃₎
Starts communication as partner modem responds (step S _14).

CCITT V. Some modems do not send an answer tone when receiving a call, even if they comply with 25 bis. When such a modulator / demodulator is accessed according to the procedure of the flow chart of FIG. 3, communication is not possible, so when the user of the modulator / demodulator monitors the line and determines that the partner modulator / demodulator is not transmitting an answer tone signal. Had set the calling side modulation / demodulation device to start communication as shown in the flowchart of FIG. 4, and performed the calling operation again.

[0004]

[Problems to be Solved by the Invention] CCITT V. 25
A user who does not know that some bis-compliant modulators / demodulators do not send an answer tone signal, or a user who cannot judge the presence or absence of an answer tone signal even by monitoring the line, is a conventional modulator / demodulator (see FIG. 3). Communication is not possible if a device that performs a call operation is used.

In addition, when the modulator / demodulator performs the calling operation without judging the presence or absence of the answer tone signal, there is a problem that the communication state is erroneously entered even if the other party is not the modulator / demodulator.

In order to prevent such a situation, the carrier wave of the response side modulation / demodulation device may be detected, but since one detector is switched and used as shown in the flowchart of FIG. Since the time and the detection time of the detector cannot be sufficiently secured, it was impossible to monitor the three signals.

The present invention has been made in view of the above points, and an object thereof is CCITTV. It is an object of the present invention to provide a modulation / demodulation device that can be easily used even by a user who does not know that some 25bis-compliant modulation / demodulation devices do not transmit answer tone signals.

[0008]

According to the present invention, in a modulator / demodulator for a public line, a judging section for judging the presence or absence of an answer tone signal for each telephone number of a partner apparatus, and a memory for storing the judgment result of the judging section. CCIT within a predetermined time
T (International Telegraph and Telephone Advisory Committee) V. When the answer tone signal is not detected by the calling operation conforming to the 25bis system, or when the answer tone signal is not stored in the storage unit, the frequency of the detector is switched to the carrier wave to perform a predetermined calling operation. It is characterized by

[0009]

The determination unit determines whether or not the partner modulation / demodulation device is transmitting an answer tone signal, and the determination result is stored in the storage unit together with the telephone number of the partner device. When the answer tone signal is not detected or when the answer tone signal is not stored in the storage unit, the detector is switched to the carrier wave and the calling operation is performed. Therefore, the repeated CCITT V. It is possible to prevent the repeated calling operation conforming to 25 bis. It can be used without knowing that the counterpart modulation / demodulation device does not send the answer tone signal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, a judging section for judging the presence / absence of an answer tone signal for each telephone number of the counterpart modulation / demodulation device and a memory for storing the judgment result are provided. The calling operation is CCITT V.5 as shown in the flowchart of FIG. It is performed according to 25 bis. That is, the first processing is performed in steps S ₁ and S _2.
From S to S ₄ , the presence or absence of an answer tone signal is determined in step S ₉ . As a result, if there is an answer tone signal, the telephone number and answer tone signal are written in the memory in step S ₁₇ , and communication is started in step S ₁₈ . If there is no answer tone signal, the calling operation is performed until the time-out time (for example, 50 seconds) is reached (step S ₁₉ ). Note If it is determined that there is a busy tone in step S _7, S ₁₃ and calling stopped in Step S ₁₅ per line under use.

If there is no response from the partner modulation / demodulation device even after the time-out period (step S ₁₉ ), after the elapse of the re-transmitting waiting time (for example, 5 seconds) (step S ₂₂ in FIG. 2), it is indicated by X in FIG. Calling operation by carrier wave is performed. That is, in steps S ₂₇ and S ₃₃ , the detector is switched to the carrier wave and the calling operation is automatically performed again. And step S ₂₈ ,
After writing to memory in step S ₃₆ if the carrier is detected in S _35, starts communication in step S _37.

[0012] Here, in order to avoid repeated re-calling operations, when it is known that there is no answer tone signal by collating the telephone number in the memory at the time of calling, step S
Operation ₄ to step S ₂₂ is not performed, performs a calling operation according to the flowchart of X portion of FIG. That is, after the second time, if it is determined that the memory is stored (step S ₂ ) and the answer tone signal is not present (step S ₃ ), the process immediately proceeds to step S ₂₃ and the detector is switched to the carrier wave to automatically The call operation is carried out.

[0013]

As described above, according to the present invention, the determination unit and the storage unit are provided, and the frequency of the detector is switched to the carrier when it is known that the other device does not respond or there is no answer tone signal. Since the calling operation is performed by the above, the following excellent effects can be obtained.

(1) It can be used even by a person who does not know that there is a part of the modulation / demodulation device that does not send the answer tone signal.

(2) It can be used even by a person who cannot judge the presence or absence of an answer tone signal by monitoring the line.

(3) Even if a device other than the modulation / demodulation device responds, the communication state does not occur.

(4) Since the result of the automatic determination of the presence or absence of the answer tone is stored in the memory, the connection after the second time can be made promptly.

[Brief description of drawings]

FIG. 1 is a flowchart showing the first half of an operation procedure of an apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the latter half of the operation procedure of the device according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an example of an operation procedure of a conventional modulation / demodulation device.

FIG. 4 is a flowchart showing another example of the operation procedure of the conventional modulation / demodulation device.

Claims (1)

[Claims] 1. A public line modulation / demodulation device is provided with a determination unit that determines the presence or absence of an answer tone signal for each telephone number of a partner device, and a storage unit that stores the determination result of the determination unit, within a predetermined time. CCITT (International Telegraph and Telephone Advisory Committee) V. When the answer tone signal is not detected by the calling operation conforming to the 25bis system, or when the answer tone signal is not stored in the storage unit, the frequency of the detector is switched to the carrier wave to perform a predetermined calling operation. A modulation / demodulation device characterized by the above.