Relaying device and monitoring method of voice communication

[Problem] Provided is a relaying device that can track and record a communicated voice of a specific communication terminal using a mixing function of the relaying device.[Solution] When a communication terminal has sent a call packet to call another at least one communication terminal, a communication session in which this communication terminal that has made a call and a communication terminal that has been called are participating terminals is established. In the communication session, voice communication is relayed by transferring a voice signal which is transmitted from the participating terminals to another at least one communication terminal. A virtual device is registered as a participating terminal of the communication session and the voice signal which is transmitted from the communication session to the virtual device is recorded in the relaying device.

TECHNICAL FIELD

The present invention relates to a relaying device that relays voice communication, and more particularly to a recording function of a voice signal to be relaying.

BACKGROUND ART

Relaying devices that relay voice communication such as radio transceiver, a telephone, or the like made by a network are proposed (refer to Patent Literature 1, 2, and 3). As a result of connecting a plurality of relaying devices to a network, it is also possible that different type of communication apparatuses such as IP telephone and radio perform voice communication to each other. If the relaying device outputs a relaying voice signal to outside, it is possible to record the voice signal.

CITATION LIST

PROBLEMS TO BE SOLVED BY INVENTION

However, in order for a relaying device configured as described above to output a voice signal to the outside of the relaying device, a device for external output needs to participated in the communication, and new hardware is needed. Also, although it is possible to realize recording of the communication by software, it takes time and effort to add a new recording function to the relaying device, and a new burden is imposed on a control unit that performs relaying processing of voice communication.

Therefore, the present invention aims to provide a relaying device that can record the communicated voice in the relaying device using a mixing function of the relaying device.

SUMMARY OF INVENTION

A relaying device according to the present invention includes a communication unit configured to communicate with a plurality of communication terminals that perform voice communication, a communication session processing unit configured to, when one communication terminal has called another at least one communication terminal, establish a communication session in which the communication terminal that has called and the at least one communication terminal that has been called are registered as participating terminals, and upon a voice signal being transmitted from a participating terminal in the established communication session, transmit this voice signal to another participating terminal in the same communication session, and a communication monitoring unit configured to register a virtual device that is a virtual communication terminal as a participating terminal of the communication session, acquire a voice signal transmitted from the communication session processing unit to the virtual device, and record or reproduce the voice signal.

A monitoring method of the voice communication according to the present invention, in the relaying device that communicates with the plurality of communication terminals that perform voice communication, establishes the communication session in which the communication terminal that has called and the at least one communication terminal that has been called are registered as participating terminals when one communication terminal has called another at least one communication terminal, transmits this voice signal to another participating terminal in the same communication session when the voice signal is transmitted from a participating terminal in the established communication session, registers the virtual device as a participating terminal of the communication session that is a virtual communication terminal for transmitting the voice signal to a communication monitoring unit provided in the relaying device, and records or reproduces the voice signal transmitted from the communication session to the virtual device, by using the communication monitoring unit.

In the above-described invention, a predetermined communication device or a predetermined group consisted of a plurality of communication terminals is associated with a virtual device, and when the predetermined communication terminal or the predetermined group which is associated with the virtual device is registered as a participating terminal of a communication session, the virtual device may register as a participating terminal of the communication session.

In the above-described invention, a plurality of virtual devices may be provided, and a plurality of communication sessions maybe separately recorded or reproduced in parallel, at same time.

In the above-described invention, the communication session that includes each of a terminal that performs telephone communication, a terminal that performs wireless communication, and a terminal that performs voice communication over a network may be established.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, as a result of causing a virtual device to participate in a communication session, communicated voices of each communication session can be acquired inside the relaying device, and the voices can be recorded or output.

DETAILED DESCRIPTION OF THE EMBODIMENT

A voice communication system of the present invention will be described with reference to the drawings. FIG. is a diagram illustrating a configuration of a voice communication system1, which is an embodiment of the present invention.FIG. 2is a diagram illustrating a configuration of a relaying device2.

The voice communication system1realizes voice communication between a plurality of communication terminals by the relaying device2relaying voice signals. A SIP phone20, an extension telephone22, a WLAN transceiver23, an LTE transceiver24, an analog transceiver26, a digital transceiver28, and the like, which will be described later, are prepared as the communication terminals. These communication terminals are devices that transmit and receive voice signals in forms that are different to each other, and the relaying device2relays voice communication between these different types of communication terminals.

The relaying device2can monitor voices in communication. When two or more communication terminals communicate to each other, the relaying device2establishes a communication session for this communication. The relaying device2can establish a plurality of communication sessions at the same time, but selects and monitors, from the established sessions, a communication session in which a specific communication terminal (or a group) participates. The monitoring means is one of or both of recording and audio output.

InFIG. 1, the relaying device2relays voice communication between a plurality of communication systems including an IP telephone system13, a WLAN transceiver system14, an LTE transceiver system15, and a wireless communication system16. The relaying device2includes a telephone relaying unit3, a network communication relaying unit4, and a wireless communication relaying unit5in order to perform these relays.

The IP telephone system13is connected to the telephone relaying unit3. The IP telephone system13includes the SIP phone20and a VoIP gateway21that are connected to a network10, and the extension telephone22connected to the VoIP gateway21. The VoIP gateway21has a PBX function and is also connected to a telephone line (external line).

A network10including a wireless access point (not illustrated) and an LTE communication network11including a base station (not illustrated) are connected to the network communication relaying unit4. The WLAN transceiver system14is constructed on the network10, and the LTE transceiver system15is constructed on the LTE communication network11. The WLAN transceiver system14includes WLAN transceivers23that access the network10via the wireless access point. The LTE transceiver system15includes LTE transceivers24that access the LTE communication network11via the base station. The configuration and functions of the network communication relaying unit4are described in detail in WO 2015/068663, which is a prior patent application of this applicant.

As shown inFIG. 2, a plurality of the external apparatus interfaces34, which are portions of a signal processing unit33are connected to the wireless communication relaying unit5. An analog-type radio transceiver (repeater)25and a digital-type radio transceiver (repeater)27are connected to the external apparatus interfaces34. The repeater25communicates with a handy radio transceiver (analog transceiver)26of the same analog type. The repeater27communicates with a handy radio transceiver (digital transceiver)28of the same digital type. The configuration and functions of the wireless communication relaying unit5are described in detail in JP 2014-087027A and WO 2016/002866, which are prior patent applications of this applicant.

FIG. 2is a block diagram of the relaying device2. The relaying device2includes the telephone relaying unit3, the network communication relaying unit4, the wireless communication relaying unit5, and a communication monitoring unit6. The functions of these units are mainly realized by software. The relaying device2includes a control unit30. The control unit30is constituted by a computer including a CPU, a ROM, a RAM, and the like. An external storage device7, a network connection unit31, an LTE connection unit32, and the signal processing unit33are connected to the control unit30. The external storage device7is a nonvolatile and large capacity storage device such as a USB hard disk, for example, and stores a voice file in which a communicated voice of a communication terminal is recorded. The network connection unit31is connected to the networks10. The LTE connection unit32is connected to the LTE communication network11. Although the networks10connected to the telephone relaying unit3and the network communication relaying unit4are separately described inFIG. 1, these networks maybe the same.

In the relaying device2, the functions of the telephone relaying unit3, the network communication relaying unit4, the wireless communication relaying unit5, and the communication monitoring unit6are realized by cooperation between hardware including the control unit30and software. The telephone relaying unit3includes an interface3A for transmitting and receiving a voice signal and the like to and from the network communication relaying unit4. The network communication relaying unit4includes an interface4A for transmitting and receiving a voice signal and the like to and from the wireless communication relaying unit5. Also, the wireless communication relaying unit5includes an interface5A for transmitting and receiving a voice signal and the like to and from the signal processing unit33. The signal processing unit33extracts a voice signal from an RTP packet received from the control unit30(interface5A), converts the voice signal to a digital or analog signal wave, and outputs the signal wave to the external apparatus interface34. Also, the signal processing unit33compresses and encodes a digital or analog voice signal received from the external apparatus interface34, and also packetizes the encoded data into an RTP packet, and inputs the RTP packet to the control unit30(interface5A).

Three external apparatus interfaces34(34-1to34-3) are provided, namely an analog interface34-1, a digital interface34-2, and an analog (microphone at hand/speaker) interface34-3. A state in which repeaters25and27are respectively connected to the analog interface34-1and the digital interface34-2is shown inFIG. 1.

The network communication relaying unit4relays communication between the WLAN transceivers23, communication between the LTE transceivers24, and communication between a WLAN transceiver23and an LTE transceiver24. Also, in response to a call from the telephone relaying unit3, the network communication relaying unit4relays communication between the telephone20or22(SIP phone20, extension telephone22) and a WLAN transceiver23or an LTE transceiver24, and the communication between the telephone20or22and the radio transceiver26or28. Also, the control of a communication session and the mixing of voice signals, which will be described later, are executed by the network communication relaying unit4. The network communication relaying unit4corresponds to a communication session processing unit of the present invention.

The telephone relaying unit3, upon receiving a call from the SIP phone20or the extension telephone22, determines the communication partner communication apparatus (destination radio), which is the call destination, and inputs the information regarding the destination radio and the voice signal received from the telephone20or22to the network communication relaying unit4. It should be noted that the entirety or some of the telephone relaying unit3, the network communication relaying unit4, and the wireless communication relaying unit5including the signal processing unit33corresponds to a communication unit of the present invention.

The communication monitoring unit6monitors voices in a communication session in which, out of the plurality of communication terminals, the communication terminal to be monitored participates. As described above, the monitoring refers to recording and/or outputting a communicated voice. In the following description, a case where recording is performed will be described. Recorded voices (voice files) are stored in the external storage device7.

Each communication terminal is registered in a terminal table (call destination table)40shown inFIG. 3A. A user who intends to start communication calls a communication terminal of the communication partner using a possessing communication terminal. As a result of this call operation, a call message is generated and transmitted to the relaying device2. Upon the relaying device2receiving the call message, the relaying device2registers the communication session to a mixing table41shown inFIG. 3B(establishes the communication session), and calls the communication terminal of the communication partner. With this, communication between the communication terminals is started.

The communication terminals excluding the telephones20and22start communication by transmitting an RIP packet in which a voice signal is stored as a data body. That is, communication is started in a form such as a radio transceiver with which communication is started by a PTT switch being pressed. The RTP packet that is first transmitted when starting communication is referred to as a call packet. This call packet functions as the call message. This RTP packet used in the voice communication system1is configured as shown inFIG. 4. On the other hand, when the telephone20or22starts communication, first, the telephone transmits a SIP message (INVITE) to the relaying device2. The relaying device2establishes a communication session with another communication apparatus following a SIP procedure. In the following description, a case will be described where, as a result of a communication terminal such as the WLAN transceiver23transmitting a call packet, a communication session is established.

Various types of tables to be provided in the control unit30of the relaying device2will be described with reference toFIGS. 3A to 3D.FIG. 3Ais a diagram illustrating the terminal table (call destination table)40. Pieces of information regarding each communication terminal and each group that are registered in the voice communication system1are registered in the terminal table40. A plurality of communication terminals belong to each group, and when the group is called, the plurality of communication terminals that belong to the group are simultaneously called. In association with each communication terminal, an identification number (ID), address information for accessing the communication terminal, and a participating session number indicating the communication session in which the communication terminal is participating are stored in the terminal table40. With respect to each registered group, the identification numbers of communication terminals that belong to this group are stored. The identification number (ID) corresponds to identification information of the present invention. In this table, the group “plenary” to which all the communication terminals belong is treated similarly to other groups.

It should be noted that the call type is information indicating that, when this ID is called, what type of communication will be executed. “Individual” communication indicates one to one communication between individual communication terminals. “Group” communication is communication in which a plurality of communication terminals (three or more, in general) exchange voice signals to each other. “Plenary” communication is communication in which all the communicable communication terminals that are connected to the network10, the LTE communication network11, and the external apparatus interface34exchange voice signals to each other.

When a communication terminal calls another communication terminal, the communication terminal transmits an RIP packet (voice packet) in which the identification number (destination ID) of the communication terminal to be called is written, to the relaying device2.FIG. 4is a diagram illustrating a configuration of the RTP packet to be used in this voice communication system. The RTP packet includes a header and a data body (payload), and a transmission destination address and a transmission source address are described in the header. The data body includes a voice signal and session information for voice communication. The session information is information regarding a communication session to be registered in the mixing table41inFIG. 3B, and with this, the communication session to which this RTP packet relates to can be identified. The session information includes a session number, a destination ID, and a calling ID. It should be noted that in the case of a call packet that is a voice packet to be transmitted first when communication is started, because the communication session for this voice packet is not yet established (communication session is not registered in the mixing table41), the session number field is empty.

FIG. 3Bis a diagram illustrating the mixing table41. A communication session that has been established and is being executed is registered in the mixing table41. The relaying device2transfers a voice signal received from one communication terminal that is participating in a communication session to at least one other communication terminal that is participating in the communication session. If a plurality of voice signals are input at the same time, these voice signals are mixed and transmitted to communication terminals. Even in a case where voice signals are mixed and transmitted to each communication terminal, the relaying device2performs echo-canceling mixing for the communication terminal such that a voice signal transmitted from this communication terminal is not returned to the same communication terminal.

The mixing table41is provided with a session number field, a calling ID field, a destination ID field, a participating terminal field, an excluded terminal field, and a retention time timer (TS) field for each communication session. The session number is a number for identifying the communication session, and is assigned a serial number that indicates the order of establishment (order of registration) of the communication session. The identification number of a communication terminal that has made a call (transmitted a call packet) is stored in the calling ID field. The identification number of a communication terminal or a group that has been called by the call packet is stored in the destination ID field.

The identification number of a communication terminal that is participating in the communication session is registered in the participating terminal field. Also, the identification number of a communication terminal that has been called in (belongs to) the communication session but is not participating in the communication session, because the communication terminal is participating in another communication session and performs communication, is registered in the excluded terminal field. When a voice signal is transmitted from one communication terminal (participating terminal) whose identification number is registered in the participating terminal field, the control unit30transfers this voice signal to the other participating terminal(s).

In the case of the group communication session, the identification number of a calling terminal and the identification numbers of communication terminals that belong to the group designated as the communication partner are registered in the participating terminal field. Note that a communication terminal that belongs to the group, but is participating in a different communication session is excluded from the participating terminal, because the communication terminal cannot participate in the group communication session, and the identification number thereof is registered in the excluded terminal field. Also, if the calling terminal is a communication terminal that does not belong to the group, which is a case where the calling terminal calls a group other than the group to which the calling terminal belongs, the identification number of the calling terminal is also registered in the participating terminal field. In the case of a plenary communication session, all of the communication terminals that can perform communication are registered as the participating terminals.

The retention time of each communication session is set to 30 seconds, for example. The retention time timer (TS) in the mixing table41is a timer that is counted down when a voice signal is transmitted from none of the participating terminals. The retention time timer TS is reset by communication session management processing (refer toFIG. 9) (30 seconds being set), and is also counted down. If a voice signal is transmitted from none of the participating terminals for 30 seconds, and the time counted down by the timer TS reaches this communication session is canceled, and the information regarding this communication session is erased from the mixing table41.

FIG. 3Cis a diagram illustrating a priority table42. The priority of each call type of communication is stored in the priority table42. The priority is represented by a numerical value, and the smaller the value is, the priority is higher. In the case where one communication terminal is called from a plurality of communication sessions in an overlapped manner, which of the communication sessions the communication terminal is to be participated in is determined based on the priorities in the priority table42. The case where one communication terminal is called from a plurality of communication sessions in an overlapped manner includes a case where the communication terminal is called from a plurality of communication sessions at the same time, and a case where, while the communication terminal is participating in one communication session, the communication terminal is called from another communication session, for example.

It should be noted that if the priority of the current communication session and the priority of a new communication session are the same, the communication terminal continues to participate in the current session, and will not move to the new communication session. The configuration may also be such that the communication terminal is moved to the new communication session even if the priorities are the same. Also, the contents of the priority table42are not limited thereto, and the individual communication session may be priority number 1, for example.

FIG. 3Dis a diagram illustrating a virtual device table43. In the virtual device table43, the identification code (such as VD1) of a virtual device and the identification number (ID) of a recording target (a communication terminal or a group that is to be monitored) are stored in an associated manner. When a communication session in which a communication terminal of an identification number in this table participates is established, the corresponding virtual device is caused to participate in this communication session. The mixing function of the communication session also transmits the voice signals that are transmitted and received in the communication session to the virtual device. The communication monitoring unit6acquires and records the voice signals. The virtual device is a virtually working device that is caused to participate in the communication session in order to acquire voice signals for recording, from a function unit (network communication relaying unit4) that performs mixing of voice signals, and the communication monitoring unit6causes the virtual device to participate in the communication session in which the communication target participates. With this, the network communication relaying unit4outputs voice signals to the communication monitoring unit6as the voice signals to be transmitted to the virtual device when mixing is performed, and the communication monitoring unit6can acquire all of the voice signals of the communication session (in which the recording target is participating). When the recording target has left the communication session, the virtual device also leaves the session. The configuration may also be such that the communication monitoring unit6outputs voice signals to a speaker or the like for allowing the user to hear, and recording (or without recording) the voice signals of the communication session that is the recording target.

While the details will be described later with reference to a flowchart, the communication monitoring unit6continuously buffers voices in the communication session that the recording target is participating, divides the voice data into data of a predetermined size (e.g. 100 MB), and makes a file of the data. Also, when the state of a communication session in which the recording target is participating is changed, e.g. when the communication session in which the recording target is participating is started/moved/ended, a file of the buffered voice signals is made at the timing of each change of the state.

The relaying device2transmits voice packets (voice signals), that is transmitted from a communication terminal and that is input over the network10or via the LTE communication network11or the external apparatus interface34, to another communication terminal further over the network10or via the LTE communication network11or the external apparatus interface34. In the case of the group communication, a voice signal is transmitted to a plurality of communication terminals that belong to the group. Also, in the case of the group communication, there are cases where the users of a plurality of communication terminals speak at the same time, and voice packets are transmitted from the plurality of communication terminals at the same time. In such a case, the relaying device2edits new voice packets by mixing these voice signals of the plurality of voice packets, and transmits these new voice packets to the respective communication terminals. It should be noted that a voice packet in which all of the voice signals are mixed is transmitted to a communication terminal that has not transmitted a voice signal, and with respect to a communication terminal that has transmitted a voice signal, a voice packet in which all of the voice signals excluding the voice signal that the communication terminal has transmitted are mixed is transmitted to the communication terminal. With this, an echo of a voice signal that a communication terminal has transmitted will not occur in the communication terminal. Besides, in the case of performing communication in a form of the plenary communication as well, mixing is performed in a manner similar to the group communication. Since a virtual device does not transmits a voice signal, all of the voice signals in the communication session is transmitted to the virtual device.

The operations of the relaying device2will be described with reference to the flowcharts inFIGS. 5 to 11.FIG. 5illustrates the processing operations of the control unit30at the time of receiving a voice packet. Upon receiving a voice packet, the control unit30reads session information of this voice packet, and determines whether or not the communication session has already been registered in the mixing table41(step S10). If the communication session has already been registered in the mixing table41(YES in step S10), the control unit30transmits the voice signal of the received voice packet to at least one other communication terminal that is participating in the communication session by referring to the participating terminal field of the mixing table41(step S17). The control unit30further resets the retention time timer TS in the mixing table41to 30 seconds (step S18).

If the communication session of the received voice packet is not registered in the mixing table41(NO in step S10), that is, if this voice packet is a call packet, which is a first voice packet, the control unit30performs registration processing for registering a new communication session due to this voice packet to the mixing table41(step S11). Hereinafter, this registration processing will be described usingFIG. 6.

FIG. 6is a flowchart illustrating operations of the registration processing of the communication session that is executed in step S11inFIG. 5. The control unit30extracts participating terminal candidates constituted by the calling terminal and communication terminals to be called in the new communication session based on the destination ID and the calling ID included in the received call packet, and selects one of the participating terminal candidates (step S20). Next, the control unit30determines whether or not the communication terminal of this participating terminal candidate is engaged (participating in another communication session) (step S21). If it is determined, in step S21, that the communication terminal is not engaged (NO in step S21), the control unit30determines that this communication terminal is a participating terminal of the communication session to be established this time (step S22). The control unit30determines whether this communication terminal is a recording target communication terminal (step S23). If the communication terminal is a recording target (YES in step S23), a virtual device VDn associated with this communication terminal is also included in the participating terminals (step S24).

If it is determined, in step S21, that the communication terminal of this participating terminal candidate is engaged (YES in step S21), the control unit30compares the priority of the communication session in which this communication terminal is currently participating with the priority of this new communication session (step S25). If the priority of the new communication session is higher (YES in step S25), the control unit30executes leaving processing for causing this communication terminal to leave the currently participating communication session (step S26), and determines that this communication terminal as the participating terminal of the new communication session (step S22). If this communication terminal is a recording target (YES instep S23), the control unit30also includes a corresponding virtual device VDn in the participating terminals (step S24). In step S25, if the priority of the new communication session is the same as or lower than the priority of the communication session in which this communication terminal is currently participating (NO in step S25), the control unit30does not cause this communication terminal to participate in the new communication session, and determines to be an excluded terminal of the new communication session (step S27). The control unit30repeats the processing from step S20to step S27with respect to all of the participating terminal candidates (step S28).

If the processing described above has been executed with respect to all of the participating terminal candidates (YES in step S28), the control unit30determines the number of communication terminals that have been determined as the participating terminals (step S29). If the number of participating terminals excluding the virtual devices is two or more (YES in step S29), the control unit30registers this new communication session to the mixing table41(step S30), and ends this processing. Also, in step S29, if the number of participating terminals is less than two (NO in step S29), the control unit30determines that this new communication session cannot be established, and does not register the new communication session to the mixing table41, and ends this registration processing.

Returning toFIG. 5, the control unit30determines, in step S12, whether or not a new communication session has been registered in the communication session registration processing (step S11inFIG. 6). If a new communication session has not been registered (NO in step S12), the control unit30ends the processing incurred by the reception of this voice packet. On the other hand, if a new communication session has been registered in step S12(YES in step S12), the control unit30, if the virtual device is included in the participating terminals (YES in step S13), starts buffering of the new communication session is started (step S14), and transfers the voice signal of the received voice packet to a communication terminal that is participating in the communication session by referring to the participating terminal field of the mixing table41(step S15).

Next, the session leaving processing to be executed in step S26inFIG. 6will be described with reference toFIG. 7. This processing is processing for causing a communication terminal that is participating in a communication session to leave the communication session in order to move the communication terminal to another communication session whose priority is higher, as shown inFIG. 6. The control unit30erases the participating session number in the terminal table (step S40), and moves the identification number of this communication terminal from the participating terminal field, in the mixing table41, of the communication session that the communication terminal is currently participating to the excluded terminal field (step S41). Then, it is determined whether this communication terminal is a recording target or not (step S42). If this communication terminal is a recording target (YES instep S42), the control unit30erases the virtual device VDn from the participating terminal field (step S43), stops recording (buffering) of this communication session, and makes a file of the data of voice that has been buffered until this point in time (step S44). If, as a result of the communication terminal having left the communication session, the number of the participating terminals thereof has decreased to less than two (YES in step S45), session ending processing for ending this communication session (step S46) is executed (step S46). If the recording target communication terminal has left the communication session, recording is immediately started in a communication session in which this communication terminal has newly participated (See step S24inFIG. 6and step S14inFIG. 5).

FIG. 8is a flowchart illustrating the session ending processing. This processing is executed when, as a result of a participating terminal having left, the number of participating terminals has decreased to less than two, as described above, and when the voices in the communication session have stopped, and a predetermined time (30 seconds) has elapsed in a soundless state. The control unit30selects one participating terminal in the communication session that is caused to be ended (step S50), erases the participating session number of this communication terminal in the terminal table40(step S51), and determines whether this communication terminal is a recording target (step S52). If it is determined to be a recording target (YES in step S52), the control unit30erases the virtual device VDn from the participating terminal field (step S53), stops recording (buffering) of this communication session, and makes a file of the data of voice that has been buffered until this point in time (step S54).

The control unit30searches whether the identification number of this communication terminal is registered in the excluded terminal fields of the other communication sessions registered in the mixing table41(step S55). If a communication session in which this communication terminal is registered as an excluded terminal is present (YES in step S56), in order to make the excluded communication terminal participate in this communication session in which the communication terminal has been excluded, the control unit30moves the identification number of this communication terminal from the excluded terminal field to the participating terminal field of this communication session (step S57), and writes the session number of this communication session to the participating session number field of this communication terminal in the terminal table40(step S58). The control unit30then determines whether this communication terminal is a recording target (step S59). If it is determined to be a recording target (YES in step S59), the control unit30writes the virtual device VDn in the participating terminal field of the communication session (step S60), and starts recording (buffering) of this communication session (step S61). After having executed the processing from step S50to step S61with respect to all of the participating terminals (YES in step S62), the control unit30erases this communication session from the mixing table41(step S63), and ends the session ending processing.

FIG. 9is a flowchart illustrating the communication session management processing. In the communication session management processing, the control unit30counts the soundless time of each communication session registered in the mixing table41, and when a predetermined time (30 seconds) has elapsed, ends the communication session. This processing is regularly (e.g. every 20 milliseconds) executed repeatedly. The control unit30, first, designates the communication session in the first row of the mixing table41(step S80). The control unit30reduces the retention time timer TS of the designated communication session by one count (20 milliseconds worth) (step S81), and determines whether or not the retention time timer TS reaches0due to this reduction (step S82). If the retention time timer TS reaches 0 (YES in step S82), the control unit30determines that this communication session has ended, and erases the session ending processing with respect to the communication session of this row (step S83,FIG. 8). The control unit30manages the mixing table41by successively performing the processing described above until the last row of the mixing table41(steps S84and S85).

FIG. 10is a flowchart illustrating recording management processing operations to be executed by the communication monitoring unit6of the control unit30. This processing is a processing for managing the communication session and executed at fixed intervals (20 milliseconds) with respect to a virtual device VDn. First, the communication monitoring unit6sets “1” to “n” (step S90), and selects the virtual device VDn (step S91). The communication monitoring unit6determines whether or not this virtual device VDn is recording data of voice, that is, determines whether or not the communication terminal which is a recording target is participating in the communication session (step S92). If the data of voice of the communication session are being recorded (YES in step S92), the communication monitoring unit6determines whether or not size of the buffered recorded voice reaches a predetermined size (100 MB) (step S93). If the size of the buffered data of recorded voice reaches 100 MB (YES in step S93), the communication monitoring unit6makes a file of the buffered recorded voice and deletes the buffered recorded voice until this point in time (step S94). Note that newly recorded voice is continuously buffered. If the virtual device VDn is not recording voice (NO in step S92), and the size of the buffered recorded voice does not reach 100 MB, the communication monitoring unit6performs nothing. While sequentially adding “1” to “n” (step S96), processing of step S90to step S94are performed, and the processing are ended after abovementioned processing are performed to all the virtual device VDn (YES in step S95).

A file of recorded voices (voice files) are stored in the external storage device7. In the external storage device7, a saving directory “voice_data[n]” (n is the virtual device number) for saving recorded voices is created for each virtual device VDn (n=1 to 4). A folder for each date is created under each directory. “Date in which saving is started” is used as the folder name. For example, the folder for the virtual device VD1 for Sep. 10, 2018 is “/voice_data1/20180910”. Also, the file name of a voice file that is created every 100 MB is named such that a communication type is added to MM (month) DD (day) HH (hour) DD (minutes) SS (seconds) at which buffering has started. The communication type includes “_all” in the case of plenary communication, “_group100” (100 is a group ID) in the case of group communication, “_uid10” (transceiver ID) or “_tel1234” (telephone number of IP telephone) in the case of individual communication, and the like. For example, the file name of a voice signal in a communication session having a group ID 100 whose buffering has started at 18:01 on September 10th is “0910180100_group100.wav”. Therefore, the voice signal of the communication session having the group ID 100 with respect to which the virtual device VD1 has started buffering at 18:01 on September 10th is saved as “/voice data1/20180910/0910180100_group100.wav”, for example.

In the above-described embodiment, the recorded voice data is in WAVE format, but an any encoded format can be used. An MP3 format can be used, for example. Also, when capacity of the external storage device7is not sufficient, older files of recorded voice may be sequentially deleted (overwritten).

In the above-described embodiment, although a virtual device table43is provided and the virtual device is associated with the communication terminal or the communication group, the virtual device may be associated with the communication terminal or the communication group by a user of the relaying device2without making the virtual device associate with the communication terminal or the communication group in advance.

Also, in the present embodiment, a file is made every time the size of the buffered recorded voice reaches a predetermined size, but a file may be made every time the recording time reaches a predetermined time length.

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