JP2010283585A - Communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To temporarily change a detection level (threshold) of a reception signal for detecting a DTMF (dual tone multi frequency) signal or a facsimile signal from a preset threshold to a threshold in receiving the DTMF signal. <P>SOLUTION: This communication terminal 10 is equipped with: a control part 11; and a modem part 13 including a level detection part 13d and a DTMF detection part 13b, and is configured to set a threshold for detecting a reception signal in the level detection part 13d, at a value suitable for reception of a facsimile signal. In the communication terminal, when the DTMF detection part 13b detects reception of the DTMF signal, the level detection part 13d determines the reception level of the DTMF signal, the threshold value is temporarily changed to a value suitable for reception of the DTMF signal based on the reception level of the DTMF signal determined by the level detection part to receive the DTMF signal, and the threshold value is restored to a value suitable for reception of the facsimile signal by the end of the reception of the DTMF signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention can remotely set a communication terminal device capable of remotely operating various functions, for example, an answering machine function, based on a DTMF (Dual Tone Multi Frequency) signal received from the outside via a telephone line. The present invention relates to a communication terminal device such as a facsimile machine.

  Conventionally, there has been provided a communication terminal device capable of remotely operating various functions based on a DTMF signal received from the outside via a telephone line. For example, in a facsimile apparatus having an answering machine function, a function such as an answering machine function in the facsimile apparatus is remotely operated based on a DTMF signal received from the outside via a telephone line.

  In such a conventional facsimile apparatus, it is necessary to detect a DTMF signal which is a remote control signal. As a configuration for detecting a DTMF signal (tone signal), a tone signal from a primary / secondary separation circuit such as a transformer is amplified by a single amplifier at a single amplification degree, and the amplified signal is supplied to a tone signal detection circuit. In general, the input is used.

  A communication terminal device such as a remotely operable facsimile device is disclosed in, for example, the following Patent Document 1 (Japanese Patent Laid-Open No. 2001-186291) and Patent Document 2 (Japanese Patent Laid-Open No. 9-51385).

  Patent Document 1 discloses a facsimile apparatus that switches between a recording paper reception mode and a memory reception mode by remote operation using a DTMF signal or the like, and Patent Document 2 discloses remote operation by a remote control signal. In a communication terminal device, a communication terminal device is disclosed in which a remote control signal from a remote terminal and a remote control signal from a nearby terminal can be appropriately detected.

  The facsimile apparatus disclosed in Patent Document 1 includes a reading unit that reads line by line, a line i / f unit for connecting to a public line, and a line i / f that modulates digital image data, and analog Modem means for outputting a signal; memory means for storing received images; visualizing means for visualizing read images and received images; voice analyzing means for analyzing voice data from the line; In accordance with the analysis result by the voice analysis means, a memory reception mode for storing the received FAX image in the memory, and a reception mode switching means for switching between the recording paper reception mode for printing out and not leaving the memory are configured. It is a thing.

  The communication terminal device disclosed in Patent Document 2 is a communication terminal device remotely operated by a remote control signal, amplifies the received signal with an amplifier, and detects the remote control signal based on the amplified signal. When receiving a remote control signal from a nearby terminal and when receiving a remote control signal from a remote terminal, the amplification factor of the amplifier is changed and the remote control signal from the remote terminal is changed to a proximity The remote control signal from the connected terminal can be appropriately detected.

JP 2001-186291 A JP 09-51385 A

  By the way, in a communication terminal device having a remote operation function using a DTMF signal from the outside via a conventional telephone line, the reception sensitivity of a DTMF signal for remote operation such as a facsimile signal and an answering machine is received in advance. Generally, a value that satisfies the sensitivity is selected, a common threshold value (one threshold value) is set, and these received signals are detected.

  As described above, when a common threshold value (one threshold value) is set and a DTMF signal or a facsimile signal is detected, if sufficient reception sensitivity is secured for facsimile communication, the sensitivity of the DTMF signal is excessively increased. An echo signal at the circuit end may be erroneously detected as a DTMF signal, and a failure such as double detection of the DTMF signal may occur.

  In particular, recently, diversification of communication lines causes problems such as arrival of unnecessary signals such as echoes and distortions on the lines, and significant attenuation. For example, communication terminal apparatuses are connected not only to an analog public telephone network (PSTN) but also to various line networks such as an ISDN line network and a VOIP network. For this reason, depending on the connected line, the received signal may be significantly attenuated. When a common threshold value is set to detect a DTMF signal and a facsimile signal, it is difficult to set a threshold value that satisfies both detections. .

  Therefore, if a threshold value sufficient for receiving a facsimile signal is set as a common threshold value for detecting both the DTMF signal and the facsimile signal, the detection sensitivity is excessively increased in the detection of the DTMF signal, and the echo on the line is reduced. There is an inconvenience that a DTMF signal may be erroneously detected and a DTMF double detection error may occur. For this reason, there has been a problem that the reception sensitivity of the facsimile signal must be lowered and priority should be given to measures against erroneous detection of DTMF. In this case, there arises a problem that the reception of the facsimile reception signal is hindered.

  However, the facsimile apparatus disclosed in Patent Document 1 switches between the recording paper reception mode and the memory reception mode by remote operation using a DTMF signal or the like, and solves the above problems. No technique has been suggested. The communication terminal device disclosed in Patent Document 2 receives a remote control signal from a nearby terminal when the received signal is amplified by an amplifier and a remote control signal is detected based on the amplified signal. In some cases, the remote control signal is detected by changing the amplification degree of the amplifier depending on when the remote control signal is received from a remote terminal, and the above-mentioned problems cannot be solved.

  The inventor of the present application has conducted various studies to solve the above problems, and as a result, has a remote operation function using an external DTMF signal via a telephone line. In the determined type of facsimile apparatus, the normal threshold value is set to a value that satisfies the reception sensitivity of the facsimile signal. When a DTMF signal is received, a detection level suitable for DTMF detection can be obtained based on the arrival level (reception signal level). The present invention has been completed by conceiving that the above problems can be solved if the threshold value is temporarily changed.

  That is, the present invention has an object to solve the above problems, and a received signal for detecting a DTMF signal or a facsimile signal in a communication terminal apparatus such as a facsimile apparatus capable of remotely setting an answering machine function or the like. It is an object of the present invention to provide a communication terminal device that can temporarily change the detection level (threshold value) from a preset threshold value when receiving a DTMF signal.

  In order to solve the above problems, the invention according to claim 1 of the present application is a communication terminal device connected to a telephone line network and capable of voice communication and facsimile communication, wherein the function of the communication terminal device is controlled by a DTMF signal. In the communication terminal device capable of remote control, the communication terminal device includes a control unit, and a modem unit having a level detection unit and a DTMF detection unit, and the communication terminal device receives at the level detection unit. The threshold for signal detection is configured to set an appropriate value for reception of a facsimile signal, and when the DTMF detection unit detects reception of a DTMF signal, the level detection unit receives a reception level of the received DTMF signal. Based on the reception level of the DTMF signal determined by the level detection unit, the threshold value is temporarily set to a value suitable for reception of the DTMF signal. Change receives the DTMF signal, characterized in that no back to an appropriate value to the reception of the facsimile signal the threshold value by the receiving end of the DTMF signal.

The communication terminal apparatus according to claim 2 of the present application is characterized in that, in the communication terminal apparatus according to claim 1, the end of reception of the DTMF signal is determined based on a preset DTMF monitoring time.
Further, in the communication terminal device according to claim 3 of the present application, in the communication terminal device according to claim 1, the reception end determination of the DTMF signal indicates whether the reception processing of the last digit of the predetermined DTMF signal has ended. It is characterized by being performed by judging.

  In the invention according to claim 1, the communication terminal apparatus includes a control unit, a modem unit having a level detection unit and a DTMF detection unit, and sets a threshold value for detecting a received signal in the level detection unit as a value of the facsimile signal. When the DTMF detection unit detects reception of the DTMF signal, the level detection unit determines the reception level of the received DTMF signal, and the level detection unit determines the reception level of the DTMF signal. Based on the reception level, the threshold value is temporarily changed to a value appropriate for reception of the DTMF signal, the DTMF signal is received, and the threshold value is returned to a value appropriate for reception of the facsimile signal when reception of the DTMF signal is completed. According to such a configuration, it is possible to correctly perform facsimile signal reception processing, and it is possible to prevent double detection of a DTMF signal by echoes when a DTMF signal is received.

  In the invention according to claims 2 and 3, in the invention according to claim 1, the end of reception of the DTMF signal is determined based on a preset DTMF monitoring time, or the last digit of a predetermined DTMF signal Since it is performed by determining whether or not the reception process has been completed, the threshold value can be returned to a value appropriate for reception of the facsimile signal after the reception process of the DTMF signal is completed.

It is a block diagram which shows the structure of the communication terminal device concerning the Example of this invention. It is a block diagram which shows schematic structure of the modem part of the communication terminal device shown in FIG. It is a flowchart which shows the schematic process sequence at the time of the standby of the communication terminal device concerning the Example of this invention. It is a flowchart which shows the detailed procedure of the state monitoring process of the communication terminal device concerning the Example of this invention. It is a flowchart which shows the other procedure of the state monitoring process of the communication terminal device concerning the Example of this invention.

  Hereinafter, specific examples of the present invention will be described in detail with reference to examples and drawings. However, the embodiments described below exemplify a communication terminal device for embodying the technical idea of the present invention, and are not intended to identify the present invention as this communication terminal device. The present invention can be equally applied to communication terminal devices of other embodiments included in the scope of claims.

  FIG. 1 is a block diagram of the configuration of the communication terminal apparatus according to the first embodiment of the present invention. The communication terminal device 10 includes a control unit 11, a display / operation unit 12, a modem unit 13, a memory unit 14, a dialer unit 15, an NCU unit 16, a speech network unit 17, a power supply unit 18, and the like.

  The control unit 11 is mainly composed of a microprocessor, and includes a memory such as a ROM as in a general computer device. The control unit 11 reads various control programs stored in the ROM and performs operations in a memory unit 14 to be described later. The memory area is expanded and the operation of each unit is controlled according to the control program.

  The display / operation unit 12 includes, for example, a display unit including a display panel such as an LCD or an organic ELD, an operation button having a numeric keypad or various function keys, a touch panel such as a resistive film type or a sensor type. Various information such as a destination number at the time of dial input is displayed in accordance with a control signal from the control unit 11.

  Further, the display / operation unit 12 inputs a destination number by inputting required alphanumeric characters and character symbols from the operation buttons, or pressing or touching the keypad displayed on the touch panel with a finger or a pen. And from the phone book data stored in the memory unit 14, an operation instruction such as a call for data desired by the user is received, and the received various operation instructions are output to the control means 11 as operation control signals. Various operations can be performed.

  The modem unit 13 is connected to the NCU unit 16, communicates via the NCU unit under the control of the control unit 11, and receives signals used for a caller telephone number guidance service and the like to the control unit 11. Notice. Various signals such as image information used for facsimile communication transmitted and received via the NCU unit 16 are modulated and demodulated.

  The memory unit 14 is a readable / writable non-volatile memory such as a flash memory including a calculation memory area used by the control unit 11 and a storage memory area for storing various data such as device setting information and speed dials. It is configured.

  The dialer unit 15 sends a dial signal consisting of a pulse or DTMF to the telephone line L via the NCU unit 16 based on the telephone number information input from the numeric keypad of the display / operation unit 12 under the control of the control unit 11. . In order to control the connection between the telephone line L and the modem unit 13 under the control of the control unit 11, the NCU unit 16 shapes the incoming signal into a pulse signal, detects the incoming signal, and releases / closes the line. Then, a dial signal from the dialer unit 15 is transmitted to call a communication partner.

  The speech network unit 17 is connected to the handset 17a, detects on-hook and off-hook of the handset 17a, performs input / output and amplification of voice signals via a speaker and a microphone provided in the handset 17a, and the like. Is for doing. The power supply unit 18 is connected to a commercial power supply and supplies power to the entire communication terminal device 10.

  The modem unit 13 receives a signal transmitted through the telephone line via the NCU unit 16 when the communication terminal device 10 is connected to the line and uses it, and first performs tone detection, and the line is a tone line. It is determined whether there is a pulse line.

  Also, the modem unit 13 sends a response message to the line after receiving the incoming call from the line. When the modem unit 13 detects the DTMF signal, the modem unit 13 notifies the control unit 11 of the detection result, and performs reception processing of the DTMF digit signal. The unit 11 switches to a function corresponding to the received 4-digit DTMF signal, for example, an answering machine function. Further, when the modem unit 13 detects a facsimile signal (detects CNG indicating that the transmission side is performing facsimile transmission), the control unit 11 is notified of the detection result and performs facsimile reception processing.

  The modem unit 13 detects the level (energy) of a signal received via the NCU unit 16 in order to detect tone, detect a DTMF signal, or CNG. In the modem unit 13 according to the present embodiment, the level detection threshold is set to a threshold sufficient to receive the facsimile signal reliably, for example, -43.5 dBm.

  When the modem unit 13 detects the DTMF signal, the modem unit 13 detects the level of the received signal. If the reception level of the DTMF signal is, for example, a level exceeding -35 dBm, the modem unit 13 sets the threshold for level detection to -43.5 dBm until at least the first digit of the DTMF signal is detected. Is changed to an appropriate value sufficient for detecting a DTMF signal, for example, -37 dBm, temporarily receiving four digits of the DTMF signal, and when reception is completed, the process returns to the original threshold, that is, -43.5 dBm. I do.

  Thus, by changing the threshold for level detection temporarily to an appropriate value necessary for receiving the DTMF signal by receiving the DTMF signal, the echo is not detected as a DTMF signal even if the signal is attenuated, and When a facsimile signal is received, a threshold sufficient for receiving the facsimile signal can be used, and the received signal is not erroneously detected.

  FIG. 2 is a functional block diagram showing a schematic configuration of the modem unit 13 shown in FIG. In the functional block diagram of FIG. 2, only functional parts related to the present invention are shown, and functional parts necessary for voice call when a voice band signal is received are omitted.

  As shown in FIG. 2, the modem unit 13 includes a tone detection unit 13a that detects a tone, a DTMF detection unit 13b, a CNG detection unit 13c, a level detection unit d, and the like. The DTMF signal received from the line is detected by the DTMF detector 13b as to what type of DTMF signal is detected, and the signal level of the detected DTMF signal is detected by the level detector d. Similarly, the tone signal received from the line is detected by the tone detector 13a, and the signal level of the detected tone signal is detected by the level detector d. Similarly, for the CNG signal, the signal level of the CNG signal detected by the level detector d is detected. CNG is a signal of a predetermined pattern indicating that the caller is a facsimile machine (repeatedly receiving a signal of 1100 Hz for 5 seconds with a pause time of 3 seconds).

  The reception signal detection level of the level detection unit 13d is set to an appropriate value for receiving a facsimile signal in the initial state, in this case, -43.5 dBm. The level detection unit 13d detects the level of the signal received via the NCU unit 16 using this threshold value in the initial state.

  When the CNG detection unit 13c detects the facsimile signal, the modem unit 13 notifies the control unit 11 of the detection result and causes the control unit 11 to perform facsimile signal reception processing. When the DTMF detection unit 13b detects the DTMF signal, the modem unit 13 detects the signal level of the received DTMF signal by the level detection unit 13d. If the reception level of the DTMF signal is, for example, a level exceeding -35 dBm, the modem unit 13 sets the threshold for level detection to -43.5 dBm until at least the first digit of the DTMF signal is detected. Is changed to an appropriate value sufficient for detecting the DTMF signal, for example, -37 dBm, and the 4-digit reception of the DTMF signal is performed. When the reception is completed, the process returns to the original threshold, that is, -43.5 dBm. I do. At that time, the modem unit 13 notifies the detection result of the DTMF detection unit 13b to the control unit 11, causes the control unit 11 to perform reception processing of the DTMF digit signal, and the control unit 11 receives the received four-digit signal. Switching to a function corresponding to the DTMF signal, for example, an answering machine function is performed.

  Next, the operation procedure of the communication terminal device 10 according to the embodiment of the present invention described above will be described with reference to the flowcharts shown in FIGS. FIG. 3 is a flowchart showing a schematic processing procedure during standby of the communication terminal apparatus 10 according to the embodiment of the present invention, and FIG. 4 is a detailed state monitoring process of the communication terminal apparatus 10 according to the embodiment of the present invention. It is a flowchart which shows a procedure.

  In the flowchart shown in FIG. 3, when the communication terminal device 10 is turned on and enters a standby state, the cold start portion is initially set in the process of step S1. In this initial setting, various system settings necessary for initializing the processor portion of the communication terminal device 10 are performed. Next, the process proceeds to step S2, and initial setting of the hot start portion is performed. The initial setting here is processing for setting parameters (initial values) necessary for the operation of various applications of the communication terminal device 10.

  Next, the communication terminal device 10 sets a detection threshold value of the level detection unit 13d of the modem unit 13, that is, a threshold value of the reception level (reception sensitivity) in the process of step S3. The threshold value set here is -43.5 dBm which is appropriate for receiving a facsimile signal. When these settings are completed, the communication terminal apparatus 10 enters the state monitoring in step S4 and detects the occurrence of an event. The occurrence of an event is, for example, detection of a DTMF signal, detection of a facsimile signal, or detection of a reception signal in a voice band. When the occurrence of an event is detected, the process proceeds to step S5, and a process corresponding to the event that has occurred is performed.

  FIG. 4 is a flowchart showing the procedure of the state monitoring process, and shows the processing procedure for monitoring the state of a signal received from the telephone line via the NCU unit 16. In the flowchart of FIG. 4, the arrow from step S2 to step S2 indicates a transition from the process of step S2 of FIG. 3 or a transition to the process of step S2. The control unit 11 first determines whether or not the line is captured (step S21). If it is determined in step S21 that the communication terminal device 10 is not capturing a line (NO in step S21), the process proceeds to step S30, and another monitoring job is performed.

  If it is determined in step S21 that the line is captured (YES in step S21), the level detection unit 13d of the modem unit 13 detects the reception level of the signal received from the telephone line via the NCU unit 16. To do. This level detection threshold is −43.5 dBm, which is initially set in step S3 of FIG. Therefore, when the received signal is a facsimile signal, a detection level sufficient to receive the received signal is guaranteed.

  Next, the tone detector 13a of the modem unit 13 detects the tone of the received signal. If no tone is detected (NO in step S22), the process proceeds to step S31, and the process proceeds to monitoring other events. When a tone is detected (YES in step S22), the DTMF detector 13b determines whether or not the received signal is a DTMF signal (first digit) (step S23). If no DTMF signal is detected (NO in step S23), the process proceeds to step S32, and the CNG detector 13d determines whether the received signal is a facsimile signal.

  If it is determined in the determination process of step S32 that the received signal is not a facsimile signal (NO in step S32), the process proceeds to step S34, and the process proceeds to another tone detection process. If it is determined that the received signal is a facsimile signal (YES in step S32), the process proceeds to step S33 to receive a facsimile.

  On the other hand, when DTMF is detected in the determination process in step S23 (YES in step S23), the level detection unit 13d detects the reception level of the DTMF signal and determines whether or not it is equal to or higher than the determination level of the DTMF signal (step S23). S24). If it is not higher than the determination level, the process proceeds to step S26, and the control unit 11 performs reception processing for the first digit of the DTMF signal.

  If the determination process in step S24 determines that the DTMF signal is equal to or higher than the predetermined determination level (YES in step S24), the modem unit 13 sets the threshold value of the received signal detection level in the level detection unit 13d to receive the DTMF signal. An appropriate value is set and temporarily changed (step S25). That is, if the reception level of the DTMF signal exceeds about -35 dBm, an appropriate value sufficient for detecting the DTMF signal, for example, the threshold is temporarily changed to -37 dBm, and the DTMF signal is received.

  After the process of step S25, the modem unit 13 notifies the detection result of the received signal to the control unit 11, and the control unit 11 performs the first digit detection process of the DTMF signal (step S26). At that time, the modem unit 13 determines the time for DTMF monitoring using a timer unit (not shown) and performs time monitoring. The monitoring time may be a time sufficient for detection processing of at least four digits of the DTMF signal. Further, instead of a method of monitoring time, it may be a process of determining whether or not a four-digit DTMF signal has been received.

  After the process of step S26, the modem unit 13 determines whether or not the DTMF monitoring time has expired (step S27). If it is determined that the DTMF monitoring time has ended (YES in step S27), the process proceeds to step S35, and the detection threshold of the level detection unit 13d is initialized (returned to -43.5 dBm). If it is determined that the DTMF monitoring time has not ended (NO in step S26), the DTMF detector 13b detects reception of a DTMF signal (step S28). In step S26, the inter-digit monitoring time is set to about 10 seconds, for example.

If the DTMF signal is not detected in step S28, the process returns to step S27. If the DTMF signal is detected, the process proceeds to step S29, and the modem unit 13 notifies the control unit 11 of the detection result of the received signal. Then, the control unit 11 performs detection processing for the second and subsequent digits of the DTMF signal (step S29), and returns to the processing of step S27. The modem unit 13 repeats the processing from step S27 to step S29 until the reception and processing of the four digits of the DTMF signal is completed.
In step S29, the inter-digit monitoring time is set to about 10 seconds, for example.

  In the above-described processing of the first embodiment, an example is shown in which time monitoring is performed using a timer in the DTMF signal detection procedure (see step S27 in FIG. 4), but whether or not reception of four digits of DTMF has been completed. It is also possible to take a procedure for monitoring. FIG. 5 is a flowchart showing a procedure for monitoring whether or not reception of four digits of DTMF is completed.

  In the flowchart shown in FIG. 5, the processes in steps S41 to S46 and the processes in steps S51 to S56 correspond to the processes in steps S21 to S26 and the processes in steps S30 to S35 in the flowchart shown in FIG. In the procedure of FIG. 5, processing in steps S47 to S50 different from the procedure of FIG. 4 will be described below.

  That is, when the first digit detection process of the DTMF signal is performed in the process of step S46, the process proceeds to the process of step S47, and the time monitoring is performed by setting the processing time for four digits of the DTMF signal as the monitoring time. When the monitoring time has ended (YES in step S47), the process proceeds to step S56, and the detection threshold value of the level detection unit 13d is initialized (returned to -43.5 dBm). If it is determined that the monitoring time is not over (NO in step S47), the DTMF detection unit 13b detects reception of the DTMF signal (step S48).

  If the DTMF signal is not detected in step S48, the process returns to step S47. If the DTMF signal is detected, the process proceeds to step S49, and the modem unit 13 notifies the control unit 11 of the detection result of the received signal. And the control part 11 performs the detection process after the 2nd digit of a DTMF signal (step S49). Next, the process proceeds to step S50, and the modem unit 13 determines whether or not the reception process up to the fourth digit of the DTMF signal has been completed.

  If the reception process up to the fourth digit of the DTMF signal has not been completed (NO in step S50), the process returns to step S47, and this process is repeated until the reception process up to the fourth digit of the DTMF signal is completed. . If it is determined that the reception process up to the fourth digit of the DTMF signal has been completed (YES in step S50), the process proceeds to step S56, and the detection threshold of the level detection unit 13d is initialized (to -43.5 dBm). return).

  As described above, according to the communication terminal apparatus according to the present invention, the reception signal detection level (threshold value) for detecting the DTMF signal or the facsimile signal is temporarily set from the preset threshold value when the DTMF signal is received. Therefore, it is possible to correctly perform facsimile signal reception processing and to prevent double detection of the DTMF signal by echo when receiving the DTMF signal.

DESCRIPTION OF SYMBOLS 10 ... Communication terminal device 11 ... Control part 12 ... Display / operation part 13 ... Modem part 14 ... Memory part 15 ... Dialer part 16 ... NCU 17 ··· Speech network 18 ··· Power supply 13a · · · Level detector 13b · · · Tone detector 13c · · · DTMF detector 13d · · · CNG detector

Claims (3)

A communication terminal device connected to a telephone line network and capable of voice communication and facsimile communication, wherein the function of the communication terminal device can be remotely controlled by a DTMF signal.
The communication terminal device includes a control unit, a modem unit having a level detection unit and a DTMF detection unit,
The communication terminal device is configured to set a threshold value for detection of a reception signal in the level detection unit to an appropriate value for reception of a facsimile signal, and when the DTMF detection unit detects reception of a DTMF signal, The level detection unit determines a reception level of the received DTMF signal, and temporarily changes the threshold to a value suitable for reception of the DTMF signal based on the reception level of the DTMF signal determined by the level detection unit. A communication terminal device which receives a DTMF signal and returns the threshold to a value suitable for reception of a facsimile signal upon completion of reception of the DTMF signal.   The communication terminal apparatus according to claim 1, wherein the end of reception of the DTMF signal is determined based on a preset DTMF monitoring time.   The communication terminal apparatus according to claim 1, wherein the reception end determination of the DTMF signal is performed by determining whether or not the reception processing of the last digit of a predetermined DTMF signal is ended.

Images