阅读说明：本技术 中继装置以及声音信号的中继方法 (Relay device and method for relaying audio signal ) 是由 园部博崇 于 2019-04-26 设计创作，主要内容包括：在跨越中继装置呼叫通信对方的通信设备的情况下,能够根据通信对方的功能来切换声音信号的发送控制方式。中继装置(2)具备电话中继部(3)、网络通信中继部(4)以及无线通信中继部(5)。无线通信中继部5具备多个外部设备接口,模拟中继器(25)、数字中继器(27)等与各外部设备接口连接。在从SIP电话机(20)向模拟收发器(27)存在呼叫的情况下,根据呼叫信息得出模拟收发器(27)的地址、设备类别,以模拟收发器(27)中存在的发送控制方式(VOX方式)将声音信号发送至模拟收发器(27)。(When a communication device of a communication partner is called across relay apparatuses, the transmission control method of an audio signal can be switched according to the function of the communication partner. A relay device (2) is provided with a telephone relay unit (3), a network communication relay unit (4), and a wireless communication relay unit (5). The wireless communication relay unit 5 includes a plurality of external device interfaces, and an analog relay unit (25), a digital relay unit (27), and the like are connected to the respective external device interfaces. When a call is made from an SIP telephone (20) to an analog transceiver (27), the address and device type of the analog transceiver (27) are obtained from the call information, and an audio signal is transmitted to the analog transceiver (27) in a transmission control method (VOX method) existing in the analog transceiver (27).)

1. A relay device is provided with: a telephone relay section and a wireless communication relay section,

the relay device is characterized in that it is provided with,

the telephone relay unit receives call information from a telephone via a network, transmits and receives an audio signal to and from the telephone after responding to a communication partner specified by the call information,

the wireless communication relay unit is connected to a relay serving as a relay wireless device, and transmits and receives an audio signal to and from the wireless device via the relay,

the telephone relay unit determines a target device of a wireless device to be called based on the call information received from the telephone, and transfers an audio signal received from the telephone to the wireless communication relay unit,

the wireless communication relay section forwards the sound signal forwarded from the telephone relay section to the target device,

the telephone relay unit determines a transfer control method of the audio signal corresponding to the determined target device, and transfers the audio signal to the wireless communication relay unit in the determined method.

2. The relay device of claim 1,

the forwarding control mode of the sound signal is any one of the following modes: a constant transmission mode for transmitting an audio signal without interruption in communication between the telephone and the target device; a VOX system for transmitting an audio signal only when the audio signal is input from a telephone at a predetermined level or higher; alternatively, the DTMF scheme is a scheme in which the transfer of the audio signal is performed without interruption after the audio signal instructing the start of transmission is input until the audio signal instructing the stop of transmission is input.

3. The relay device of claim 1 or claim 2,

the telephone relay unit includes:

a call destination table for storing, for each of the wireless devices, a record including the call information, the address of the target device, and the device type of the target device; and

a transfer control table for storing a record including the device type and a transfer control method of the audio signal for each device type,

the telephone relay unit determines the device type of the destination device with reference to the call destination table, determines the transfer control method of the audio signal corresponding to the determined device type with reference to the transfer control table, and transfers the audio signal in the determined transfer control method.

4. The relay device of claim 3,

the transfer control table stores a transfer control method of the audio signal matching the transmission/reception function of the audio signal provided by the target device in association with the device type.

5. The relay device of claim 3 or claim 4,

the relay device further includes:

a network communication relay unit which is connected to the WLAN transceiver which starts to transmit the audio signal to the communication partner without performing a predetermined call procedure via the network, and is connected to the LTE transceiver which starts to transmit the audio signal to the communication partner without performing a predetermined call procedure via an LTE network which is a communication network of the mobile phone,

the call destination table and the forwarding control table store the call information, the address of the target device, the device type, and the forwarding control method of the audio signal, which use the WLAN transceiver and the LTE transceiver as the target devices.

6. A relay device according to any one of claims 3 to 5,

the call destination table also stores records of group communications targeted to the plurality of communication devices.

7. A method for relaying an audio signal,

in a relay device connected with a telephone and a relay wireless device for communicating with the wireless device,

receiving call information for calling the wireless device from the telephone set,

deciding a target device of a radio device to be called based on the call information,

determining a transfer control method of the audio signal corresponding to the determined target device,

calling the target device via the repeater,

after the target apparatus responds, the sound signal received from the telephone set is forwarded to the repeater in the decided forwarding control manner.

8. The method of relaying a sound signal according to claim 7,

the forwarding control mode of the sound signal is any one of the following modes: a constant transmission mode for transmitting an audio signal without interruption in communication between the telephone and the target device; a VOX system for transmitting an audio signal only when the audio signal is input from a telephone at a predetermined level or higher; alternatively, the DTMF scheme is a scheme in which the transfer of the audio signal is performed without interruption after the audio signal instructing the start of transmission is input until the audio signal instructing the stop of transmission is input.

9. The method of relaying a sound signal according to claim 7 or claim 8,

determining the device type of the target device by referring to a call destination table, the call destination table storing, for each of the wireless devices, a record including the call information, the address of the target device, and the device type of the target device,

and determining a transfer control method of the audio signal corresponding to the determined device type by referring to a transfer control table, wherein the transfer control table stores a record including the device type and the transfer control method of the audio signal for each device type.

10. The method of relaying a sound signal according to claim 9,

the transfer control table stores a transfer control method of the audio signal matching the transmission/reception function of the audio signal provided by the target device in association with the device type.

11. The method of relaying a sound signal according to claim 9,

the relay device is further connected to: a WLAN transceiver for starting to transmit a voice signal to a communication partner without performing a previous call procedure; and an LTE transceiver which starts transmitting a voice signal to a communication partner without performing a previous call procedure,

the call destination table and the forwarding control table store the call information, the address of the target device, the device type, and the forwarding control method of the audio signal, which are targeted devices using the WLAN transceiver and the LTE transceiver.

12. The method of relaying a sound signal according to any one of claims 9 to 11,

the call destination table also stores records of group communications with a plurality of communication devices as target devices.

Technical Field

The present invention relates to a relay device for relaying communication between a telephone and a wireless device, and more particularly to optimization of transfer control of an audio signal.

Background

Relay devices that relay audio communications such as wireless transceivers and telephones via a network have been proposed (see patent documents 1, 2, and 3). By connecting a plurality of relay devices to a network, it is possible to make an IP telephone and different types of communication equipment such as a wireless device perform voice communication with each other.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2014-087027

Patent document 2: international publication WO2015/068663 gazette

Patent document 3: international publication WO2016/002866

Disclosure of Invention

Problems to be solved by the invention

When 2 relay devices are connected to each other via a network to relay audio communication between different types of communication apparatuses as described above, the function of the communication apparatus on the receiving side cannot be known from the transmitting side. Therefore, the transmitting side cannot control the transmission of the audio signal in accordance with the function of the receiving side, and can transmit the audio signal only in a predetermined fixed manner. For example, when a wireless device is called from a telephone that performs full duplex communication and performs communication, if the communication function (full duplex/half duplex) of the wireless device to be called is known, it is determined whether the voice signal is to be transmitted in the constant transmission mode or the VOX mode according to the function.

Therefore, an object of the present invention is to enable switching of a transmission control scheme of an audio signal according to a function of a communication partner when calling a communication device of the communication partner across a relay apparatus.

Means for solving the problems

A relay device of the present invention includes a telephone relay unit and a wireless communication relay unit. The telephone relay unit receives call information from the telephone via the network, and transmits and receives an audio signal to and from the telephone after responding to a communication partner specified by the call information. The wireless communication relay unit is connected to a relay serving as a relay wireless device, and transmits and receives audio signals to and from the wireless device via the relay. The telephone relay unit determines a target device of the wireless device to be called based on the call information received from the telephone, and transfers the audio signal received from the telephone to the wireless communication relay unit. The wireless communication relay unit forwards the voice signal forwarded from the telephone relay unit to the target device. The telephone relay unit determines a transfer control method of the audio signal corresponding to the determined target device, and transfers the audio signal to the wireless communication relay unit in the determined method.

In a relay device to which a telephone and a relay wireless device for relaying communication with the wireless device are connected, call information for calling the wireless device is received from the telephone, a target device of the wireless device to be called is determined based on the call information, a transfer control method of an audio signal corresponding to the determined target device is determined, the target device is called via the relay, and the audio signal received from the telephone is transferred to the relay in the determined transfer control method after the target device responds.

In the above invention, the transfer control method of the audio signal may be any one of the following methods: a constant transmission mode for transmitting the audio signal without interruption in the communication between the telephone and the target device; a VOX system for transmitting an audio signal only when the audio signal is input from a telephone at a predetermined level or higher; alternatively, the DTMF scheme is a scheme in which the transfer of the audio signal is performed without interruption after the audio signal instructing the start of transmission is input until the audio signal instructing the stop of transmission is input.

In the above invention, the telephone relay unit may be provided with a call destination table and a forwarding control table. The call destination table is a table in which a record including call information, an address of a target device, and a device type of the target device is stored for each wireless device. The forwarding control table is a table in which records including device types and forwarding control methods of audio signals are stored for each device type. The telephone relay unit determines the device type of the destination device with reference to the call destination table, determines the transfer control method of the audio signal corresponding to the determined device type with reference to the transfer control table, and transfers the audio signal in the determined transfer control method.

In the above invention, the transfer control table may store the transfer control method of the audio signal matching the transmission/reception function of the audio signal provided in the target device in association with the device type.

In the above invention, the relay device may include a network communication relay unit. The network communication relay unit is connected to the WLAN transceiver via a network and connected to the LTE transceiver via an LTE network. The WLAN transceiver and the LTE transceiver start transmitting an audio signal to a communication partner via the network and the LTE network, respectively, without performing a previous call procedure. The call destination table and forwarding control table store records of WLAN transceivers and LTE transceivers. The call destination table may further store a record of group communication in which a plurality of communication apparatuses are targeted.

Effects of the invention

According to the present invention, when transmitting and receiving an audio signal between different types of communication apparatuses, it is possible to perform transmission control of the audio signal in accordance with the function of the communication apparatus on the receiving side.

Drawings

Fig. 1 is a block diagram of a voice communication system.

Fig. 2 is a block diagram of a relay apparatus.

Fig. 3A is a diagram showing a call destination table provided in the relay device.

Fig. 3B is a diagram showing a PTT control table provided in the relay device.

Fig. 4 is a diagram illustrating a transmission control method of an audio signal.

Fig. 5 is a sequence diagram of the case where the analog transceiver is called from the telephone set.

Fig. 6 is a flowchart of a telephone relay section of the relay device.

Detailed Description

A voice communication system of the present invention will be explained with reference to the drawings. Fig. 1 is a configuration diagram of a voice communication system 1 according to an embodiment of the present invention. Fig. 2 is a diagram showing the configuration of the relay device 2.

The voice communication system 1 includes a relay device 2. The relay device 2 relays voice communication between a plurality of communication systems including an IP telephone system 13, a WLAN (wireless LAN) transceiver system 14, an LTE (Long Term Evolution) transceiver system 15, and a wireless communication system 16. Therefore, the relay device 2 includes a telephone relay unit 3, a network communication relay unit 4, and a wireless communication relay unit 5.

The IP telephone system 13 is connected to the telephone relay unit 3. The IP telephone system 13 includes a SIP telephone 20 connected to the network 10, a VoIP gateway 21, and an extension telephone 22 connected to the VoIP gateway 21. The VoIP gateway 21 has a PBX function and is also connected to a telephone line (external line).

A network 10 having a wireless access point (not shown) and an LTE communication network 11 having a base station (not shown) are connected to the network communication relay unit 4. A WLAN transceiver system 14 is constructed on the network 10, and an LTE transceiver system 15 is constructed on the LTE communication network 11. The WLAN transceiver system 14 has a WLAN transceiver 23 that accesses the network 10 via a wireless access point. The LTE transceiver system 15 has an LTE transceiver 24 that accesses the LTE communication network 11 via a base station. The structure and function of the network communication relay 4 are described in detail in the prior application of the present applicant, i.e., "international publication WO 2015/068663".

As shown in fig. 2, the wireless communication relay unit 5 is connected to a plurality of external device interfaces 34 as a part of the signal processing unit 33. An analog radio transceiver (repeater) 25 and a digital radio transceiver (repeater) 27 are connected to each external device interface 34. The repeater 25 communicates with a handheld wireless transceiver (analog transceiver) 26 of the same analog type. The repeater 27 communicates with a handheld wireless transceiver (digital transceiver) 28 of the same digital type. The structure and function of the wireless communication relay unit 5 are described in detail in the prior applications of the present applicant, i.e., "japanese patent application laid-open No. 2014-087027" and "international publication WO 2016/002866".

Fig. 2 is a block diagram of the relay device 2. As shown in fig. 1, the relay device 2 includes a telephone relay unit 3, a network communication relay unit 4, and a wireless communication relay unit 5, which are mainly functionally implemented by software. The relay device 2 includes a control unit 30. The control section 30 includes a computer having a CPU, ROM, RAM, and the like. The network connection unit 31, the LTE connection unit 32, and the signal processing unit 33 are connected to the control unit 30. The network connection unit 31 is connected to the network 10. The LTE connection unit 32 is connected to the LTE communication network 11. In fig. 1, the network 10 connected to the telephone relay unit 3 and the network communication relay unit 4 is shown, but the networks may be the same.

In the relay device 2, the telephone relay unit 3, the network communication relay unit 4, and the wireless communication relay unit 5 are functionally realized by cooperation of hardware and software including the control unit 30. The telephone relay unit 3 has an interface 3A for transmitting and receiving an audio signal and the like to and from the network communication relay unit 4. The network communication relay unit 4 has an interface 4A for transmitting and receiving an audio signal and the like to and from the wireless communication relay unit 5. The wireless communication relay unit 5 has an interface 5A for transmitting and receiving an audio signal to and from the signal processing unit 33. The signal processing unit 33 extracts an audio signal from the RTP packet input from the control unit 30 (interface 5A), converts the audio signal into a digital or analog signal wave, and outputs the signal wave to the external device interface 34. The signal processing unit 33 compresses, encodes, and RTP-packetizes the digital or analog audio signal input from the external device interface 34, and inputs the compressed, encoded, and RTP-packetized audio signal to the control unit 30 (interface 5A). The wireless communication relay unit 5, the signal processing unit 33, and the external device interface 34 correspond to a "wireless communication relay unit" of the present invention.

The number of the external device interfaces 34(34-1 to 3) is 3. The interfaces are respectively an analog interface 34-1, a digital interface 34-2, and an analog (microphone/speaker at hand) interface 34-3. In the example shown in fig. 1, the repeaters 25, 27 are connected to the analog interface 34-1 and the digital interface 34-2.

The network communication relay unit 4 relays communication among the WLAN transceivers 23, communication among the LTE transceivers 24, and communication between the WLAN transceivers 23 and the LTE transceivers 24. Further, the network communication relay unit 4 relays communication between the telephone sets 20 and 22(SIP telephone set 20 and extension telephone set 22) and the WLAN transceiver 23 or the LTE transceiver 24 and communication between the telephone sets 20 and 22 and the wireless transceivers 26 and 28 in response to a call from the telephone relay unit 3.

The telephone relay unit 3 receives a call from the SIP telephone 20 or the extension telephone 22, determines a communication device (target device) as a communication destination of the call, and inputs information of the target device and an audio signal received from the telephones 20 and 22 to the network communication relay unit 4.

Fig. 3 is a diagram showing various tables provided in the control unit 30 for calling and relaying communications from the telephones 20 and 22 to the WLAN transceiver 23, the LTE transceiver 24, and the analog/digital wireless transceivers 26 and 28.

Fig. 3A is a diagram showing the call destination table 37. When a call is made from the telephone sets 20 and 22 to the telephone relay unit 3, the control unit 30 refers to the call destination table 37 and determines to which communication device the call is addressed. The communication devices to be called by calling are the WLAN transceiver 23, the LTE transceiver 24, the analog transceiver 26, the digital transceiver 28, and the like that relay in the relay device 2. When the user calls any one of the communication devices individually from the telephone sets 20 and 22, the user inputs an individual call prefix "and an identification number (ID) of the communication device to be called, following the telephone number of the telephone relay unit 3 (relay device 2). Then, the SIP telephone 20 or the VoIP gateway 21 generates a call message (INVITE message) to which "telephone number of the telephone relay unit 3" + "," + "identification number" is added, and transmits the message to the telephone relay unit 3.

The telephone sets 20 and 22 can request the telephone relay unit 3 for a group call (including a general call) for simultaneously calling a plurality of communication devices. The call destination table 37 stores, in association with each identification number (ID), a communication type (individual/group/whole) designated by the identification number, a communication device type (device type) designated by the identification number, and an internal address/port number. The identification number of the group call is stored with the identification numbers of all the communication devices belonging to the group. When a call with an identification number is made from the telephone 20 or 22, the telephone relay unit 3 searches the call destination table 37 with the identification number to obtain a communication device to be a communication partner. The communication device that is the communication partner corresponds to the target device of the present invention. The identification number corresponds to the call information of the present invention.

FIG. 3B is a diagram showing the PTT control table 38. The PTT control table 38 stores transmission control schemes (constant transmission scheme, VOX scheme, and DTMF scheme) according to the types of communication apparatuses. When transmitting the audio signal received from the telephone sets 20 and 22 to the communication device of the other party, the telephone relay unit 3 refers to the PTT control table 38 and determines the transmission control scheme.

The constant transmission method, the VOX method, and the DTMF method will be described with reference to fig. 4. The constant transmission scheme is a scheme of continuously transmitting audio signals (including a silent waveform) received from the telephone sets 20 and 22 between the start of communication (off hook) and the end of communication (on hook), and corresponds to a full duplex scheme which is one of communication schemes of the transceiver. The VOX scheme is a scheme for transmitting a voice signal only when the voice signal is input from the telephone set 20 or 22 at a predetermined level or higher (which is considered to be a call voice), and corresponds to a half-duplex scheme which is one of communication schemes of a transceiver. In addition, in the IP telephone system via the network 10, the received audio signal is generally transmitted and received in the form of RTP packets. The DTMF scheme is a scheme in which, after off-hook, transmission of a voice signal is started by a PTT-on instruction tone of the user of the telephone 20 or 22, and transmission of a voice signal is terminated by the user inputting a PTT-off instruction tone. This is a device that implements a similar operation to a PTT (push-to-talk) switch in a telephone.

In the PTT control table 38, any one of the constant transmission method, the DTMF method, and the VOX method is specified for each device type of a communication device (target device). The PTT control table 38 specifies a VOX scheme in the case of a LAN transceiver and a wireless transceiver, and specifies a constant transmission scheme in the case of an LTE transceiver (telephone communication) and a microphone/speaker. In addition, in the case of collective communication or group communication, a DTMF method is designated. The transmission control method specified for each device type may be in accordance with the communication function of the communication device.

As described above, in the voice communication system of the above-described system, when a call is made from the telephone sets 20 and 22 to the telephone relay unit 3 to designate a specific communication device, the transmission control method of the voice signal is switched based on the type of the designated communication device and whether or not the designated communication device is a group call.

Referring to fig. 5, a description will be given of a sequence from call generation to the start of a call when the SIP telephone 20 (hereinafter, simply referred to as the telephone 20) among the telephones 20 and 22 calls the analog radio transceiver 26 (hereinafter, simply referred to as the radio transceiver 26). The call sequence from the telephone to the interface 3A follows SIP, omitting the display of fine responses such as "100 Trying", "180 Ringing" in the middle of the call.

When the INVITE message is transmitted from the telephone set 20 to the telephone relay section 3 (S50), the telephone relay section 3 forwards the INVITE message to the interface 3A for the purpose of calling a target device (the wireless transceiver 26 in this case) (S51). In the interface 3A, the call destination table 37 is searched by the identification number added to the INVITE message, and it is determined which communication device the call is directed to (S52). At the same time, the telephone relay unit 3 (interface 3A) searches the PTT control table 38 for the device type (analog transceiver in this example) read from the call destination table 37, and determines the transmission control method as the VOX method (S53). A call packet in the form of an RTP packet for calling the decided communication device (wireless transceiver 26) is generated (S54), and output to the network communication relay unit 4 (S55). The call packet is a data packet addressed to the address and port number described in the call destination table 37.

The call packet is forwarded from the network communication relay section 4 to the wireless communication relay section 5 based on the destination address or the like (S56). In the wireless communication relay unit 5, the call packet is converted into a call signal for calling the wireless transceiver 26 (S57), and the call signal is input to the relay unit 25 (S58). At the same time, the wireless communication relay unit 5 (external device interface 34) outputs a PTT signal to the relay unit 25. When the call signal and the PTT signal are input, the repeater 25 secures a channel that is a frequency band used for wireless communication (S59), and calls the wireless transceiver 26 using the channel (S60).

The wireless transceiver 26 that receives the call signal generates a call tone. When the user responds to the call tone (S61), a response signal is transmitted from the wireless transceiver 26 to the repeater 25 (S62). The repeater 25 inputs the response signal to the wireless communication relay unit 5 (S63). The wireless communication relay section 5 converts the response signal into a response packet (RTP packet) targeting the interface 3A of the telephone relay section 3 (S64), and transmits it to the network communication relay section 4 (S65). The network communication relay section 4 forwards the RTP packet to the forwarding interface 3A according to the destination address (S66). If the RTP packet to be replied is received, the interface 3A converts the RTP packet into a SIP message (200OK) as a response (S67), and replies the SIP message to the telephone 20 via the telephone relay 3 (S68, S69). Thereby, the telephone set 20 changes from the call state to the call state, and communication between the telephone set 20 and the wireless transceiver 26 is started (S70).

When communication is started, the telephone set 20 always continues to input the audio signal (RTP packet) to the telephone relay unit 3, but only when an audio signal of a predetermined level or more is input, the audio signal is re-edited into an RTP packet and transmitted to the network communication relay unit 4. The RTP packet re-edited here is a packet in a format in which the relay device 2 transfers the audio signal, and is different from the format used in the IP telephone.

Fig. 6 is a flowchart showing an audio signal transmission control process of the control unit 30 (the telephone relay unit 3, the interface 3A). This processing represents processing in a case where the sound signal received from the telephone set 20 or 22 is transmitted to the communication apparatus of the communication partner. When the communication between the telephone and the communication device is started (S11), the control section 30 refers to the PTT control table 38 (S12). Here, the PTT control table 38 is searched using a device type obtained by searching the call destination table 37 by the identification number attached to the INVITE message. The sound signal is transmitted in the retrieved control manner.

If the decided control mode is the VOX mode (YES at S13), the processes of S15-S17 are executed. If the decided control method is the DTMF method (NO in S13, YES in S14), the processes of S20-S24 are executed. If the decided control method is the always transmission method (no in S13, no in S14), the processing of S25-S26 is executed.

In the VOX system (yes in S13), the control unit 30 determines whether or not a sound signal of a predetermined level or higher is input (S15), and generates and transmits an RTP packet of the sound signal only when the sound signal of the predetermined level or higher is input (yes in S15) (S16). Until the communication ends (yes at S17), the above processing is continued.

In the case of the DTMF method (no in S13, yes in S14), control unit 30 determines whether or not a PTT-on instruction tone is input (S20) and whether or not a PTT-off instruction tone is input (S23), and generates and transmits an RTP packet of a sound signal until the PTT-off instruction tone is input (yes in S23) after the PTT-on instruction tone is input (yes in S20) (S22). In addition, if the communication is ended while monitoring the input of the PTT-on instruction tone (S20) and the input of the PTT-off instruction tone (S23) (yes in S21 or S24), the processing is ended.

In the case of the constant transmission method (no in S13, S14), the control unit 30 continues to generate and transmit RTP packets for the audio signal until the communication is completed (yes in S26) (S25). In any of the transmission control methods, an audio RTP packet is generated and transmitted at a predetermined time interval (for example, at 20ms intervals).

When a sound signal is input from the telephone relay section 3 (via the network communication relay section 4), the wireless communication relay section 5 inputs the sound signal to a device (a repeater or the like) connected to the external device interface 34, and performs control so that the sound signal is output. That is, when the repeater is connected, the input of the PTT signal is instructed to transmit the audio signal. In the case of the microphone/speaker 29, a sound signal is played from the speaker even if nothing is particularly done.

In the above embodiment, the processing in the case of calling the wireless transceivers 26, 28, etc. from the telephones 20, 22 is explained, but in the opposite case, that is, in the case of calling the telephones 20, 22 from the wireless transceivers 26, 28, the transmission control method of the audio signal may be determined by searching the call destination table 37 and the PTT control table 38 based on the IDs of the wireless transceivers. In this case, the call destination table 37 is used as a table for deciding the device type of the communication device of the transmission source. In this case, when the INVITE message is transmitted to the telephone sets 20 and 22, the device of the call source is specified, and therefore, the transmission control method of the audio signal is also specified, and when the telephone sets 20 and 22 respond, the audio signal from the telephone sets 20 and 22 may be transmitted to the radio transceiver of the call source or the like by the specified transmission control method.

Description of the reference numerals

1 voice communication system

2 Relay device

3 telephone relay

3A interface

4 network communication relay

5 Wireless communication relay unit

20 SIP telephone

22 extension telephone

25 analog radio (repeater)

26 analog transceiver

27 digital wireless machine (repeater)

28 digital transceiver

29 microphone/speaker

34-1 to 3 external device interfaces.