JP4857787B2 - Telephone control device - Google Patents

Description

  The present invention relates to a telephone control technique, and more particularly to a telephone control technique for performing a voice call using a spread spectrum modulation type frequency hopping technique used in a Bluetooth (registered trademark: Bluetooth) communication system.

  A telephone system comprising a telephone control device connected to a communication line and a plurality of telephone terminals accommodated in the telephone control device via an extension transmission line, and an arbitrary telephone terminal is exchanged and connected to the communication line by the telephone control device. Then, there is a configuration in which a telephone terminal (master unit) and a handset (slave unit) are connected by a Bluetooth radio communication system that is a general-purpose radio interface.

In the Bluetooth wireless communication system, a frequency hopping spread spectrum (FHSS) modulation system is used as a modulation system (see Non-Patent Document 1, etc.). This frequency hopping spread spectrum modulation system is a system in which the carrier frequency is changed at fixed intervals, that is, the frequency hopping is performed for transmission.
In general, the power of any bandwidth is low when averaged over a sufficiently long time with respect to the frequency hopping period, so it is difficult to interfere with communication of other systems, and even if there is an interference wave at a specific frequency, It is said that it is resistant to interference from other systems because it hops to a frequency.

  In the Bluetooth wireless communication system, 79 or 23 channels are provided in the 2.4 GHz band at 1 MHz intervals, and the speed is 1600 times / second based on the channel selection order set between the master side and the slave side at the start of communication. Data communication is performed by repeating frequency hopping and transmitting / receiving a desired packet to / from a counterpart wireless device using a selected channel.

Conventionally, as such frequency hopping technology, when a packet transmission / reception error occurs in an arbitrary channel due to radio waves transmitted from other devices, adaptive frequency hopping (AFH: Adaptive Frequency Hopping) disables the channel. A method is used (for example, see Non-Patent Document 2 / Bluetooth 1.2).
According to this adaptive frequency hopping method, since a channel determined to be unusable is excluded from the channel selection order, frequency hopping is no longer performed on the channel, and other channels at the carrier frequency of the channel can be used. Wireless communication interruption due to mutual interference of radio waves and collision of packet transmission / reception in the channel with the same type of telephone terminal can be reduced.

  In the adaptive frequency hopping method, the minimum number of channels is set in advance as the lower limit value of the number of usable Bluetooth channels. Therefore, if the Bluetooth channel in which a packet transmission / reception error has occurred is set to be disabled in sequence, the number of usable Bluetooth channels is reduced accordingly, but after the number of available Bluetooth channels reaches the minimum number of channels, it is optional. Even if a packet transmission / reception error occurs in the Bluetooth channel, the Bluetooth channel is not set to be unusable. This ensures a minimum number of Bluetooth channels.

http://www.bluetooth.org/spec/ http://www.ericsson.com/bluetooth/files/whitepaper_on_afh_final.pdf http://grouper.ieee.org/groups/802/11/

  However, in such a conventional technique, when a packet transmission / reception error occurs in an arbitrary channel due to a radio wave transmitted from another device, the channel cannot be used based on the adaptive frequency hopping method. When a high-load voice call using data packets is performed by a telephone terminal in a situation where the number of usable channels is reduced, the number of usable channels is insufficient, and a desired communication quality cannot be obtained for the voice call. There was a problem.

In general, streaming wireless communication such as voice communication and video communication using data packets requires a large amount of data, so it is necessary to transfer data packets sequentially without interruption. When using a Bluetooth wireless communication system telephone terminal, the frequency of channel use by the telephone terminal greatly increases.
For this reason, in a situation where the number of usable Bluetooth channels is reduced, when such streaming wireless communication is started at any telephone terminal, the frequency of channel use by the telephone terminal increases, and the same wireless area is used. The number of usable Bluetooth channels is insufficient between the telephone terminals used together, and channel collision is likely to occur.

  Therefore, when a telephone terminal (master unit) and a handset (slave unit) are connected by a Bluetooth wireless communication system in a telephone system, there is a high possibility that a plurality of voice calls are performed in the same radio area in parallel. . For this reason, compared to general wireless data communication in which data packets are transmitted and received intermittently, the use frequency of the Bluetooth channel increases for a long period of time, and channel collision is likely to occur. Also, in voice calls, if the wireless communication situation deteriorates and data packets cannot be transferred smoothly, voice interruption occurs, and the user feels the communication quality more significantly.

In addition, since the Bluetooth wireless communication system uses a Bluetooth channel provided in the ISM band, it affects the wireless communication environment in a device using the same ISM band, such as a wireless LAN communication system (see Non-Patent Document 3, etc.). In some cases.
At this time, as a technology for avoiding the deterioration of the wireless communication environment on the Bluetooth wireless telephone terminal side, priority is given to securing a frequency band used by a device other than the Bluetooth wireless communication system, such as a wireless LAN channel used in the wireless LAN communication system. A method of using a frequency band that is not used by these devices as a channel of the Bluetooth wireless communication system is conceivable.

  However, in such a method, the number of usable Bluetooth channels is limited. Therefore, when a voice call is started at any of the telephone terminals, the frequency of use of the Bluetooth channel increases for a long period of time. There is a problem that the wireless communication status of the telephone terminal is further deteriorated and the communication quality is significantly lowered.

  The present invention has been made to solve the above-described problems. Even when the number of usable wireless communication channels is reduced, a telephone control device capable of suppressing a decrease in communication quality to some extent and further improving the communication quality is provided. It is intended to provide.

In order to achieve such an object, a telephone control device according to the present invention includes a plurality of telephone terminals connected to a handset via a wireless line including a plurality of wireless communication channels having different carrier frequencies, and communication from a communication network. A telephone control device that connects a line and accommodates a telephone terminal via an extension transmission line, and realizes a telephone call with the telephone terminal by exchanging and connecting the telephone terminal and the communication line or between the telephone terminals. The terminal shares a radio communication channel between telephone terminals, stores channel management information indicating whether each radio communication channel is usable in the telephone terminal, and is set to be usable in the channel management information. Wireless communication with the handset of the telephone terminal using a wireless communication channel that is sequentially switched and selected at a predetermined cycle When a selected wireless communication channel cannot be used due to radio wave interference, it is a telephone control device used in a telephone system that sets the channel management information to disable use of the wireless communication channel, from each telephone terminal via an extension transmission line A function of storing each acquired channel management information in the storage unit in association with the telephone terminal, and a channel management means for notifying the telephone terminal of the channel management information read from the storage unit via the extension transmission path and setting it And a communication status confirmation means for confirming a wireless communication status at a telephone terminal that makes a call using a wireless communication channel among telephone terminals, and a deterioration of the wireless communication status at the telephone terminal is confirmed by the communication status confirmation means Update part or all of the unavailable channels that are set as unavailable in the channel management information of the call terminal A Yaneru opening means, with the channel opening means, when setting the usable unusable channel call terminal, one or more of using the carrier frequency corresponding to a radio frequency band used by different wireless communication systems and call terminal When the wireless communication channel is disabled according to the channel management information, the wireless communication channel is set to be enabled in order from the disabled channel located at the end of the wireless frequency band .

According to the present invention, when the telephone control device confirms the deterioration of the wireless communication status at the telephone terminal using the wireless communication channel, the unusable channel set as unusable in the channel management information of the telephone terminal. Part or all of the mobile phone is set to be usable, new channel management information is notified to the telephone terminal, and when the unusable channel of the telephone terminal is set to usable, a wireless communication method different from that of the telephone terminal is used. When one or more radio communication channels using a carrier frequency corresponding to the radio frequency band to be used are disabled by the channel management information, the channels are used in order from the unusable channel located at the end of the radio frequency band. since so as to set the variable, usable number of channels i.e. adaptive frequency hop of the telephone terminal in accordance with the deterioration of the radio communications condition It is possible to increase the number of channel candidates that can be selected based on the ring system.

At this time, there are channels that have been changed from unavailable to available, but there are channels that cannot be used regularly due to radio waves from other devices, but some of these channels happen to be used by other devices and others. There is a possibility that radio wave interference has occurred with other phone terminals, and after that, radio wave transmission from other devices is stopped, or it can actually be used according to the channel switching selection at other phone terminals Some channels have returned to the correct state.
Therefore, if the present invention is applied, in a telephone terminal used in the same radio area, the shortage of the number of usable channels is alleviated, and the occurrence of channel collision between the telephone terminals can be suppressed. It can be suppressed to some extent and further improved.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a telephone control device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the telephone control device and the telephone system according to the first embodiment of the present invention.

  This telephone system includes a telephone controller 1 connected to a communication line 10 from a communication network (not shown) such as a general button telephone system and a PBX system, and a telephone controller 1 via an extension transmission line 5. The telephone control apparatus 1 includes a plurality of telephone terminals 2 accommodated therein, and the telephone control device 1 exchanges and connects any telephone terminal 2 and the communication line 10 or between any telephone terminals 2. Realize a call with 2.

  The telephone terminal 2 is connected to the handset 3 through the wireless line 4. At this time, the telephone terminal (master side) 2 is connected to the handset (slave side) 3 via the wireless line 4 based on the adaptive frequency hopping (AFH) method of Bluetooth (registered trademark: Bluetooth) wireless communication method. By performing wireless data communication, the handset 3 is controlled and voice data is exchanged.

  In the present embodiment, each channel management information acquired from each telephone terminal via an extension transmission path by the telephone control device 1 is stored in the storage unit in association with the telephone terminal, and the updated channel management information Is set by notifying the telephone terminal via the extension transmission path, and the wireless communication status of the telephone terminal that makes a call using the wireless communication channel is confirmed, and the wireless communication situation of the telephone terminal is deteriorated. Is confirmed, part or all of the unusable channels set as unusable in the channel management information of the call terminal are updated to be usable.

[Telephone control device]
Next, the configuration of the telephone control device according to the first embodiment of the present invention will be described in detail with reference to FIG.
As shown in FIG. 1, the telephone control device 1 is an information processing device such as a computer having a communication function, and includes an external line interface unit (hereinafter referred to as an external line I / F unit) 11, an extension interface unit (hereinafter referred to as an internal line I / F). (Referred to as F section) 12, a switch section 13, a storage section 14, and a control section 15.

  The external line I / F unit 11 includes a circuit unit for connecting the communication line 10 and has a function of performing line control such as incoming call detection, outgoing call, and telephone call by terminating the communication line 10 based on a predetermined protocol. ing. At this time, the communication network includes a PSTN, ISDN, IP telephone network, PBX extension network, leased line network, etc., and the communication line 10 includes a PSTN line, ISDN line, IP telephone line (Internet), PBX extension, leased line, etc. Consists of.

The extension I / F unit 12 includes a circuit unit that performs data transmission with the telephone terminal 2 via the extension transmission path 5, and has a function of exchanging various data such as control commands and voice data with the telephone terminal 2. is doing.
The switch unit 13 includes a circuit unit that switches a call path between the external line I / F unit 11 and the internal line I / F unit 12, and switches the call path based on an instruction from the control unit 15, thereby enabling a telephone terminal 2 and the communication line 10 are arbitrarily switched and connected.

The storage unit 14 includes a storage device such as a memory and a hard disk, and has a function of storing various processing information and programs 14P used for call control processing and slave unit registration processing in the control unit 15.
The program 14P is written to the storage unit 14 from another device when the telephone control device 1 is manufactured, or is connected to an external device or a recording medium via an input / output interface provided in the telephone control device 1 such as the external line I / F unit 11. To the storage unit 14.

  Main processing information stored in the storage unit 14 includes call control information 14A and channel management information 14B. The call control information 14A includes state information indicating the state of the communication line 10 and the telephone terminal 2, and setting information indicating various setting contents. The call control information 14A is referred to when call control is performed by the control unit 15, and includes the contents of the call control. Will be updated accordingly. The channel management information 14 </ b> B is the channel management information of each telephone terminal 2 acquired via the extension transmission path 5.

  FIG. 3 is a configuration example of channel management information. Here, each channel number and whether or not the channel can be used (enabled / disabled) is registered as a set. The channel management information 14B is acquired from each telephone terminal 2 by the control unit 15 via the extension transmission path 5, and stored in the storage unit 14 in association with the telephone terminal. The updated channel management information 14 </ b> B is notified to the telephone terminal 2 through the extension transmission path 5 and set by the control unit 15.

  The availability of each channel in the channel management information 14B is updated according to the availability status of each Bluetooth channel set in the channel table by wireless communication control based on the adaptive frequency hopping method in the wireless module of the telephone terminal 2 described later. The Further, the channel management information 14B notified from the telephone control device 1 to the telephone terminal 2 is reflected in a channel table 29A of the wireless module 26 in the telephone terminal 2 to be described later, and any of the usable channels is determined based on the adaptive frequency hopping method. Are sequentially switched at a predetermined cycle and used for wireless communication with the handset.

The control unit 15 has a microprocessor such as a CPU and its peripheral circuits, and reads and executes the program 14P in the storage unit 14 to realize various functional means by cooperating the hardware and the program 14P. It is a functional part.
As main functional means realized by the control unit 15, there are a call control means 15A, a channel management means 15B, a communication status monitoring means 15C, and a channel release means 15D.

  The call control means 15A communicates using the communication line 10 by exchanging various data with a communication network (not shown) and a partner telephone (not shown) via the external line I / F unit 11 and the communication line 10. A function for connecting and disconnecting a route, a function for controlling the telephone terminal 2 by exchanging various control commands and operation information with the telephone terminal 2 via the extension I / F unit 12 and the extension transmission path 5, and a switch The telephone terminal 2 and the communication line 10 can be arbitrarily switched and connected by switching the call path between the external line I / F unit 11 and the internal line I / F unit 12 by controlling the unit 13. .

  The channel management means 15B includes a function of storing each channel management information 14B acquired from each telephone terminal 2 via the extension transmission line 5 in the storage unit 14 in association with the telephone terminal 2, and updated channel management information 14B is notified to the telephone terminal 2 via the extension transmission line 5 and set.

  The communication status monitoring unit 15C has a function of confirming the wireless communication status of a telephone terminal 2 that performs a telephone call using a wireless communication channel. Specifically, among the telephone terminals 2, the number of call terminals indicating the telephone terminals in a call state is the number of usable channels of the call terminals counted from the call terminal channel management information 14B stored in the storage unit 14. The communication status index is calculated by dividing, and when the communication status index exceeds a predetermined determination value, it is determined that the wireless communication status has deteriorated.

  When the communication status confirmation unit 15C confirms the deterioration of the wireless communication status at the call terminal, the channel release means 15D is configured to use a part of the unavailable channel set as unavailable in the channel management information 14B of the call terminal or It has a function to update everything to be usable.

[Telephone terminal]
Next, with reference to FIG. 2, the structure of the telephone terminal used with the telephone control apparatus concerning the 1st Embodiment of this invention is demonstrated in detail. FIG. 2 is a block diagram showing a configuration of a telephone terminal used in the telephone system according to the first embodiment of the present invention.
As shown in FIG. 2, the telephone terminal 2 is a telephone that is accommodated in the telephone control device 1 via an extension transmission line 5 and connected to the handset 3 via a wireless line 4. This telephone terminal (master side) 2 wirelessly communicates with a handset (slave side) 3 via a wireless line 4 based on an adaptive frequency hopping (AFH) method of Bluetooth (registered trademark: Bluetooth) wireless communication method. By performing data communication, control of the handset 3 and voice data are exchanged.

The telephone terminal 2 includes an extension interface unit (hereinafter referred to as an extension I / F unit) 20, a voice processing unit 21, a display unit 22, an operation input unit 23, a storage unit 24, a control unit 25, and a wireless module 26. ing.
The extension I / F unit 20 includes a circuit unit that performs data transmission with the telephone control device 1 via the extension transmission path 5, and functions to exchange various data such as control commands and voice data with the telephone control device 1. have.

  The audio processing unit 21 includes a dedicated signal processing circuit. The audio processing unit 21 includes audio signals input and output by a microphone and a speaker (not shown) provided in the audio processing unit 21 and audio data transmitted and received by the wireless module 26 and an extension. An incoming call based on a function for performing mutual conversion (encoding / decoding) processing on voice data transmitted / received by the I / F unit 20 and various control data received from the telephone control device 1 via the extension I / F unit 20 And a function of outputting various audio signals such as sound.

The display unit 22 includes a display device such as an LCD or an LED, and has a function of performing various visible displays in accordance with instructions from the control unit 25.
The operation input unit 23 includes an operation input device such as an operation key, and has a function of detecting a user operation and outputting the operation to the control unit 25.

The storage unit 24 includes a storage device such as a memory, and has a function of storing various processing information and programs 24P used for processing operations in the control unit 25. The program 24P is read in advance from an external device or a recording medium and stored in the storage unit 24.
Main processing information stored in the storage unit 24 includes channel management information 24A. The channel management information 24A is information indicating whether or not each Bluetooth channel used in the wireless data communication of the telephone terminal 2 can be used.

  FIG. 4 is a configuration example of channel management information. Here, each channel number and whether or not the channel can be used (enabled / disabled) is registered as a set. The availability of each channel in the channel management information 24A is updated by the control unit 25 according to the availability status of each Bluetooth channel changed by the wireless communication control based on the adaptive frequency hopping method in the wireless module 26. In addition, the channel set as unusable is updated to be usable as necessary by the control unit 25 and reflected in the wireless module 26.

The control unit 25 includes a microprocessor such as a CPU and its peripheral circuits, and reads and executes the program 14P of the storage unit 24, thereby causing the hardware and the program to cooperate with each other to realize various functional units. Have.
The main functional means includes call control means 25A and channel management means 25B.

  The call control means 25A has a function of receiving various control commands from the telephone control device 1 via the extension transmission line 5 and the extension I / F unit 20, and controls the voice processing unit 21 based on these control commands, and the radio module 26. A function for controlling the operation of the handset 3 by transmitting a control command to the handset 3 via the wireless line 4, a function for receiving operation information from the handset 3 via the wireless line 4 and the wireless module 26, and an operation input The function of detecting a user operation from the unit 23 and the function of transmitting the operation information to the telephone control device 1 via the extension I / F unit 20 and the extension transmission path 5 are provided.

  The channel management unit 25B has a function of updating the channel management information 24A based on the channel availability status read from the channel table 29A of the wireless module 26, and the telephone control device 1 via the extension transmission path 5 and the extension I / F unit 20. In response to the transfer request received from the telephone control device 24, the function of transmitting the channel management information 24 A from the extension I / F unit 20 to the telephone control device 1 via the extension transmission path 5 and the setting request received from the telephone control device 1 The new channel management information 24A included in the setting request is stored in the storage unit 24, and the channel availability information is reflected on the channel table 29A of the wireless module 26.

The wireless module 26 is a functional module that provides a wireless interface compliant with the Bluetooth wireless communication system, and a circuit unit and a processing unit that realize individual functions are integrally mounted as one component constituting the telephone terminal 2. Yes.
The wireless module 26 includes a wireless transmission / reception unit 27, a module control unit 28, and a module storage unit 29.

  The wireless transmission / reception unit 27 is a circuit unit that transmits and receives wireless signals in accordance with the Bluetooth wireless communication system, and has a function of performing wireless data communication through the wireless line 4 by transmitting and receiving wireless signals to and from the handset 3. Have. At this time, the radio transmission / reception unit 27 repeats frequency hopping based on an instruction from the module control unit 28 based on an instruction from the module control unit 28 based on an adaptive frequency hopping method, and 79 or 23 channels provided at 1 MHz intervals in the 2.4 GHz band. When data communication is performed with the handset 3 using the channel selected in step 1, and a packet transmission / reception error occurs in any channel, the channel cannot be used in sequence until the number of usable channels reaches the minimum number of channels (lower limit). And set.

The module storage unit 29 includes a storage device such as a memory, and has a function of storing various processing information used for processing operations in the module control unit 28. As main processing information stored in the module storage unit 29, there is a channel table 29A.
The channel table 29A is processing information for managing the availability of each channel that is sequentially selected by the frequency hopping spread spectrum modulation method, and the availability information of the channel is registered in association with each channel number.
In addition, the module storage unit 29 may store programs for realizing various functional units by being read and executed by the module control unit 28 in advance.

  The module control unit 28 cooperates with hardware composed of a CPU and its peripheral circuits, a memory (not shown) provided in these CPUs or peripheral circuits, and a program stored in the module storage unit 29 in advance. Functional means for controlling the wireless transmission / reception unit 27 in accordance with the Bluetooth wireless communication system is realized.

As main functional means realized by the module control unit 28, there is a communication control means 28A.
The communication control means 28A controls data transmission / reception unit 27 to control data communication between handset 3 and control unit 25, and data communication with handset 3 based on the frequency hopping / spread spectrum modulation method. A function of sequentially selecting one of the channels based on the order of channel selection decided at the start and instructing the wireless transmission / reception unit 27. At this time, the communication control unit 28A refers to the channel table 29A of the module storage unit 29, and if the next channel selected in accordance with the channel selection order is not usable, the communication control unit 28A skips to the next usable channel and allows the use. Select the channel.

  In addition, the communication control unit 28A has a function of notifying the control unit 25 of the communication status with the handset 3 in the channel selected by the adaptive frequency hopping method during data communication, and a module storage unit according to an instruction from the control unit 25. A function for updating availability information of an arbitrary channel for the 29 channel tables 29A, and a function for updating the channel table 29A of the module storage unit 29 by notifying the handset 3 in response to an instruction from the control unit 25. ing.

[Operation of First Embodiment]
Next, the operation of the telephone control device according to the first embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing the used channel revision process as the operation of the telephone control apparatus according to the first embodiment of the present invention.
Here, a case where a voice call using the handset 3 is started in response to the telephone terminal 2 in response to a user operation when an incoming call from the communication line 10 will be described.

When the telephone control device 1 detects an incoming call from a communication network (not shown) via the communication line 10 in the external line I / F unit 11, the control unit 15 uses the call control means 15A to execute the extension I / F unit. An incoming call notification command is transmitted from 12 to the telephone terminal 2 via the extension transmission path 5.
When the control unit 25 of the telephone terminal 2 receives an incoming call notification command via the extension I / F unit 20, the call control unit 25A controls the voice processing unit 21 to send a ringtone from a speaker (not shown). The incoming call is displayed by controlling the LED of the display unit 22 as well as sending out. Further, the call control means 25A transmits a control command for instructing transmission of a ringtone or display of an incoming call from the wireless module 26 to the handset 3 through the wireless line 4, and displays the incoming call by the handset 3.

Thereafter, when a response operation is performed by the user at the telephone terminal 2, the control unit 25 detects the response operation by the call control means 25 A and transmits the operation information to the extension I / F unit 20 and the extension transmission path 5. To the telephone control device 1.
The control unit 15 of the telephone control device 1 receives operation information indicating a response operation from the telephone terminal 2 via the extension I / F unit 12, and controls the switch unit 13 according to the response operation by the call control unit 15A. Then, the voice path of the communication line 10 in which the incoming call is detected among the voice paths of the external line I / F unit 11 and the voice path of the telephone terminal 2 to which the response operation is notified among the voice paths of the extension I / F unit 12. And connect.

Further, the call control means 15A transmits a call start command for instructing the start of a voice call from the extension I / F unit 12 to the telephone terminal 2 via the extension transmission path 5, and the communication line 10 and the telephone terminal 2 Is stored in the call control information 14 </ b> A of the storage unit 14.
When the control unit 25 of the telephone terminal 2 receives a call start command from the telephone control device 1 via the extension I / F unit 20, the call control unit 15A controls the voice processing unit 21 and the wireless module 26 A control command is transmitted to the handset 3 via the wireless line 4. As a result, the voice processing unit 21 converts the voice data transmitted / received by the wireless module 26 and the voice data transmitted / received by the extension I / F unit 20 to each other, and voice communication with the handset 3 via the wireless line 4 is performed. Be started.

In this way, when a voice call using the wireless line 4 is started in any of the telephone terminals 2, the control unit 15 executes the used channel revision process of FIG.
First, the control unit 15 refers to the call control information 14A in the storage unit 14 by means of the communication status monitoring unit 15C, and acquires the number of telephone terminals 2 that are currently in a call state, that is, the number of call terminals (step 100). At this time, the number of call terminals includes the call terminal 2A where the call is started. Next, the communication status monitoring unit 15C counts the number of usable channels in the call terminal 2A from the channel management information 14B in the storage unit 14, and divides the number of call terminals by the number of usable channels to thereby communicate with the call terminal 2A. A situation index is calculated (step 101). At this time, it is assumed that the channel management information 14B is sequentially acquired from each telephone terminal 2 and updated by the channel management means 15B.

This communication status index is an index indicating how much voice call is borne by one available channel in any telephone terminal 2. In the Bluetooth wireless communication system, among the wireless communication channels set in advance with different carrier frequencies, a wireless channel that does not interfere with radio waves from other devices is shared by the wireless modules to perform wireless communication. .
Here, in streaming wireless communication such as voice communication and video communication using data packets, it is necessary to sequentially transfer the data packets without interruption because of the large amount of data, and such streaming wireless communication is Bluetooth wireless. When the communication method is used, one of the usable channels is always used during the period until the wireless communication is completed, and the channel use frequency greatly increases.

  In the present embodiment, by determining the communication status index of the call terminal 2A, it is determined whether the channel usage frequency has increased due to such streaming wireless communication, that is, the communication status has deteriorated due to voice communication. The communication status at the call terminal 2 is that the number of usable channels decreases as the number of voice calls, that is, the number of call terminals increases. Therefore, the number of channels that can be selected by adaptive frequency hopping is reduced, and the channel between the phone terminals 2 is reduced. A collision at the time of selection is likely to occur, and noise and sound interruption during a voice call are likely to occur. In addition, the number of usable channels may be reduced due to radio wave interference with devices other than the telephone terminal 2, and noise and sound interruption during voice calls are likely to occur due to similar factors. The call status index increases as the number of call terminals increases, indicating that the communication status deteriorates, and when the number of usable channels decreases, the index value also increases, indicating a deterioration in communication status.

The communication status monitoring unit 15C compares the communication status index of the call terminal 2A thus obtained with a predetermined determination value (step 102).
Here, when the communication status index is equal to or smaller than the determination value (step 102: NO), there is a sufficient usable channel for the voice call, and the wireless communication at the call terminal 2A using the wireless communication channel. Since the situation is good and it is not necessary to release the unusable channel, the control unit 15 ends the series of use channel revision processing.

  On the other hand, when the communication status index exceeds the determination value (step 102: YES), the radio communication status of the call terminal 2A is deteriorated, and it is necessary to open the unusable channel and increase the usable channel. The control unit 15 sets a part or all of the unusable channels in the channel management information of the call terminal 2A among the channel management information 14B of the storage unit 14 to be usable by the channel release means 15D (step 103). .

At this time, the determination value and the number of channels set to be usable may be appropriately determined according to the channel use status in the voice call performed by the telephone terminal 2 and the communication quality required for voice communication. In addition, selection of a channel that is actually set to be usable may be appropriately selected by a general method such as channel number order or random.
The channel management means 15B reads the new channel management information 14B of the call terminal 2A revised in this way from the storage unit, and sends a setting request including this channel management information to the extension I / F unit 12 and the extension transmission path 5. Via the communication terminal 2A (step 104), and the series of used channel revision processing ends.

In response to this, in response to the setting request received from the telephone control device 1, the control unit 25 of the call terminal 2A stores the new channel management information 24A included in the setting request by the channel management unit 25B. 24, and the channel availability status is reflected in the channel table 29A of the wireless module 26.
As a result, the number of channels that can be used by the wireless module 26 is increased, and channels selected from these usable channels based on the adaptive frequency hopping method are used for wireless communication for voice calls.

  As described above, in the present embodiment, the communication status confirmation unit 15C confirms the radio communication status of the telephone terminal 2 using the radio communication channel, and the deterioration of the radio communication status of the telephone terminal 2 is confirmed. In this case, a part or all of the unusable channels set as unusable in the channel management information 14B of the telephone terminal 2 are set to be usable by the channel release means 15D, and new channel management is performed by the channel management means 15B. Since the information 14B is notified to the telephone terminal 2, the number of usable channels of the telephone terminal 2, that is, the number of channel candidates that can be selected based on the adaptive frequency hopping method can be increased.

At this time, there are channels that have been changed from unavailable to available, but there are channels that cannot be used regularly due to radio waves from other devices, but some of these channels happen to be used by other devices and others. There is a possibility that radio wave interference has occurred with other phone terminals, and after that, radio wave transmission from other devices is stopped, or it can actually be used according to the channel switching selection at other phone terminals Some channels are in a bad state.
Therefore, in the telephone terminal 2 used in the same wireless area, the shortage of the number of usable channels is alleviated, and the occurrence of channel collision between the telephone terminals 2 can be suppressed. Cutting and pulse noise can be reduced. As a result, a decrease in communication quality can be suppressed to some extent and further improved.

In a telephone system in which a plurality of telephone terminals are exchanged and connected to a communication line, when a telephone terminal (base unit) and a handset (slave unit) are connected by a Bluetooth wireless communication system, streaming is performed in the same wireless area where these telephone terminals are used There is a high possibility that voice calls, which are system radio communications, are performed in parallel with the same period.
For this reason, compared to general wireless data communication in which data packets are intermittently transmitted and received, and the data packets can be retransmitted when a transfer error occurs, the use frequency of the Bluetooth channel increases over a long period of time. Collisions are likely to occur. In voice calls, if wireless communication conditions deteriorate and data packets cannot be transmitted / received smoothly, voice interruptions and noise occur, and the user feels communication quality more significantly.

  On the other hand, if this embodiment is applied, the unusable channel set as unusable until now is changed to usable according to the deterioration of the wireless communication status at the telephone terminal using the wireless communication channel. Therefore, the number of usable channels can be increased. Thereby, even when a plurality of voice calls are performed simultaneously in the same wireless area, a certain number of usable channels can be secured. Therefore, it is possible to reduce voice interruptions and noises that occur when wireless communication conditions deteriorate and data packets cannot be transferred smoothly, and as a result, it is possible to suppress and further improve the communication quality perceived by the user to some extent. Is also possible.

  Further, in this embodiment, when confirming the wireless communication status at the call terminal 2A using the wireless communication channel, the communication status confirmation means 15C indicates a call terminal indicating a telephone terminal in a call state among the respective telephone terminals 2. The communication status index is calculated by dividing the number by the number of usable channels of the call terminal 2A counted from the channel management information of the call terminal 2A stored in the storage unit 14, and this communication status index is a predetermined determination value. Since the determination is made that the wireless communication status of the call terminal 2A has deteriorated if the value exceeds the above, the radio communication status of the call terminal 2A can be accurately and easily determined by the telephone control device 1 based on the call status of the entire telephone system. Can be determined.

Further, in the present embodiment, when starting a voice call at the call terminal 2A, the use channel revision process of FIG. 4 is executed. Therefore, when starting a voice call in which the deterioration of communication quality becomes significant, A sufficient number of usable channels can be obtained, and a response can be made in advance when the communication quality deteriorates. Further, compared with the case where the used channel revision process is always executed, the process execution can be kept to the minimum necessary, and the processing load on the control unit 15 of the telephone control device 1 can be reduced.
Note that the timing for executing the used channel revision process is not limited to the start time of the voice call. For example, when there is a sufficient processing capacity in the control unit 15, it is always performed regardless of the presence or absence of the voice call. It may be executed.

[Second Embodiment]
Next, a telephone control device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing a channel release process used in the telephone control device according to the second embodiment of the present invention.

  In the first embodiment of the present invention, when a part of unusable channels is set to be usable, which unusable channel is selected is appropriately determined by a general method such as channel number order or random. I explained that I should choose. In the present embodiment, a case will be described in which an unusable channel selected in accordance with the channel use situation in the telephone terminal 2A or other telephone terminals 2 is set to be usable. The configuration of the wireless system according to the present embodiment is almost the same as that of the first embodiment, and detailed description thereof is omitted here.

The control unit 15 of the telephone control device 1 executes the channel release process of FIG. 6 when setting the unavailable channel of the call terminal 2A to be usable by the channel release means 15D in step 103 of FIG.
First, the channel release means 15D refers to the channel management information 14B in the storage unit 14 and searches for a channel that is disabled only at the call terminal 2A (step 110). (Step 111: YES), a part or all of the target channel is set as an available channel (Step 114), and a series of channel release processing is terminated.

On the other hand, if the target channel does not exist in step 111 (step 111: NO), the channel release means 15D is set to be usable in more than half of the telephone terminals 2 among the telephone terminals 2 other than the telephone terminal 2A. If there is a target channel (step 112: YES), a part or all of the target channel is set as an available channel (step 114), and a series of channels is released. The process ends.
In step 113, if the target channel does not exist (step 113: NO), the series of channel release processing ends.

  As described above, in the present embodiment, when the unusable channel of the call terminal 2A is set to be usable, the channels other than the call terminal 2A related to these unusable channels are selected from the channels set to be unusable on the call terminal 2A. Since the target channel is searched according to the channel availability setting status of each telephone terminal 2 and a part or all of the obtained target channel is set to be usable in the channel management information of the telephone terminal. A channel that is set to be usable in the telephone terminal 2 other than the terminal 2A and has a high probability of being actually usable in the telephone terminal 2A can be selected as the target channel. Therefore, the usable channels of the call terminal 2A can be increased efficiently.

At this time, as a ratio that is set to be usable by the telephone terminals 2 other than the call terminal 2A, the case of selecting 100% of the channels corresponds to step 110 in FIG. 6, and the case of selecting 50% or more of the channels. This corresponds to step 112 in FIG. Note that these ratios may be arbitrarily selected according to the channel usage status and the call status.
Further, only one of step 110 and step 112 may be executed, but as shown in FIG. 6, step 110 and step 112 are associated in descending order of the probability that the call terminal 2A becomes an available channel. Thus, the usable channels of the call terminal 2A can be efficiently increased.

[Third Embodiment]
Next, a telephone control device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a configuration example of channel management information used in the telephone control device according to the third embodiment of the present invention.
In the first embodiment of the present invention, when a part of unusable channels is set to be usable, which unusable channel is selected is appropriately determined by a general method such as channel number order or random. I explained that I should choose. In the present embodiment, a case will be described in which the disabled channel is set to be usable in order from the oldest channel. Note that the configuration of the telephone system according to the present embodiment is almost the same as that of the first embodiment, and a detailed description thereof is omitted here.

  As shown in FIG. 7, the channel management information 14B used in the telephone control apparatus according to this embodiment is different from that of the first embodiment (FIG. 3) described above in that each channel number and its channel. In addition to the availability of availability (possible / impossible), the order in which the channel is set unavailable is set as a set. This unusable setting order corresponds to the increase in unusable channels when the channel management means 25C of the control unit 25 of the telephone terminal 2 updates the channel management information 24A of the storage unit 24 based on the channel table 29A of the wireless module 26. Thus, the channel management information 24A is set based on the past unusable setting order. The contents of the unusable setting order may be sequential numbers or date / time information.

  The channel opening means 15D of the telephone control device 1 refers to the unusable setting order in each telephone terminal 2 for each channel from the channel management information 14B when changing some of the unusable channels to usable channels. Then, calculate the statistical value such as the average value of these unavailable settings order, and based on the order of the obtained statistical values (ascending order or descending order), the order in which the unavailable channels are set is the oldest in the system Set to enable. As the statistical value, in addition to the average value, a value obtained by arbitrary statistical processing such as a minimum value, a maximum value, a representative value, and a center value can be used.

  As described above, in the Bluetooth wireless communication system, when a packet transmission / reception error occurs in an arbitrary channel due to radio waves transmitted from other devices, the channel cannot be used based on the adaptive frequency hopping system. Therefore, when a certain amount of time has passed, there is a high possibility that radio wave transmission from another device has been completed. Therefore, as in the present embodiment, by setting the usable channel in order from the oldest channel set as the unusable channel, it is possible to efficiently select a channel that can actually be used with high probability. The deterioration of quality can be more effectively suppressed.

  In the present embodiment, the channel management information 14B refers to the unusable setting order in each telephone terminal 2 for each channel, calculates a statistical value such as an average value of these unusable setting orders, and this statistical value Since the order of selection is determined based on the channel number, the channel can be selected in order from the oldest in the entire system, that is, in descending order of the probability that the call terminal 2A can be used. You can increase it well.

[Fourth Embodiment]
Next, a telephone control device according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a configuration example of wireless LAN channel management information used in the telephone control device according to the fourth embodiment of the present invention. FIG. 9 is a configuration example of the channel number conversion table. FIG. 10 is a flowchart showing a channel release process of the telephone control device according to the fourth embodiment of the present invention.

  In this embodiment, a wireless LAN communication method using the same ISM band as the Bluetooth wireless communication method is used in the same wireless area as the telephone system, and the frequency band used in the wireless LAN channel is preferentially secured, and the wireless LAN Based on the premise that a frequency band not used in the communication system is used as a channel of the Bluetooth wireless communication system, channel opening applied in such a wireless environment will be described. Here, a case will be described as an example where wireless LAN channel priority reservation is performed in common throughout the telephone system, but wireless LAN channel priority reservation may be performed individually for each telephone terminal 2.

Prioritizing the wireless LAN channel is performed by the control unit 15 of the telephone control device 1 in accordance with a user operation.
In response to the user operation notified from the telephone terminal 2, the control unit 15 acquires the channel number of the used wireless LAN channel used in the same wireless area as the telephone system from the operation content by the channel management unit 15B. Then, the Bluetooth channel number corresponding to the used wireless LAN channel is derived, and the wireless LAN channel management information 14C of the storage unit 14 is set to indicate that the Bluetooth channel is “in use”. In the configuration example of the wireless LAN channel management information shown in FIG. 8, the wireless LAN channel number and whether or not the channel is used (unused / used) are registered as a set.

  Next, the channel management means 15B searches the wireless LAN channel management information 14C for the used wireless LAN channel number that is set to “in use”, and derives a Bluetooth channel that uses the same frequency as the used wireless LAN channel. In the channel management information 14B of each telephone terminal 2 in the storage unit 14, these Bluetooth channels are set to be unusable.

  For channel conversion between the wireless LAN channel number and the Bluetooth channel number, a channel number conversion table as shown in FIG. 9 may be used, or conversion may be performed using a predetermined mathematical expression. This channel conversion is performed based on the number of unit channels. The number of unit channels is the number of Bluetooth channel channels that cannot be used when one wireless LAN channel is used.

  In addition, when the use frequency bandwidth of one wireless LAN channel is ± 10 MHz with respect to the center frequency, the use frequency bandwidth of the Bluetooth channel is 1 MHz. The Bluetooth channel corresponds to 10 channels each. At this time, a margin may be provided between the wireless LAN channel and the Bluetooth channel, for example, the number of unit channels may be set to 24.

In this manner, when priority is given to the wireless LAN channel, the number of Bluetooth channels that are selection candidates in the adaptive frequency hopping method is greatly reduced.
In the present embodiment, when such an unusable Bluetooth channel is released to be usable in such a wireless communication channel use situation, the radio frequency of the wireless LAN channel in which priority is secured by the channel opening means 15D of the control unit 15 The band is compressed and set to be usable in order from the Bluetooth channel located at the end of the radio frequency band.

For specific channel release processing, as shown in FIG. 10, first, the channel release means 15D uses the wireless LAN channel management information 14C of the storage unit 14 in the channel management information 14B of the call terminal 2A of the storage unit 14. The Bluetooth channel of the unit channel number n corresponding to the use wireless LAN channel set as “in use” is set to be usable (step 120).
Next, the number of unit channels n is reduced by the number of compressed channels dn to obtain a new number of unit channels n ′ = n−dn (step 121), and based on this new compressed unit channel number n ′, the radio used The unit number n ′ of Bluetooth channels corresponding to the LAN channel is disabled (step 122), and a series of channel release processing is terminated.

FIG. 11 is an explanatory diagram showing an operation example of the compressed channel setting process. Here, a case where channel setting is performed by compressing the wireless LAN channel 40 using the frequency band from the frequency fa to fb is shown.
When the wireless LAN channel 40 is accepted as the used wireless LAN channel number, a Bluetooth channel using frequencies from the frequency fa to fb with the center frequency f0 as the center is determined as the unusable channel 41 based on the unit channel number n. A Bluetooth channel using a frequency lower than fa and a Bluetooth channel using a frequency higher than the frequency fb are determined as usable channels 42 and 43, respectively.

Here, when it is confirmed that the number of usable channels has decreased to the number of determination channels, the number of unit channels n is reduced by the number of compressed channels dn by the channel release processing to become n ′, and the wireless LAN channel 40 The frequency band is compressed into a band from frequencies fa ′ to fb ′.
Accordingly, the unusable channel 41 is also uniformly reduced at the left and right ends around the center frequency f0, and the usable channel 42 can be used as the number of channels between the frequencies fa and fa ′ increases. As for the channel 43, the number of channels between the frequencies fb and fb ′ increases, and the number of usable channels in the entire Bluetooth channel can be increased.

  As described above, in the present embodiment, when the unusable channel is set to be usable by the channel opening means 15D, the wireless communication located at the end of the wireless frequency band used in the wireless communication method different from the telephone terminal 2 is used. Since the channels are set to be usable in order from the channel, when a plurality of radio communication channels corresponding to radio frequency bands used in a radio communication scheme different from that of the telephone terminal 2 are set to be unavailable by the channel management information However, the number of channel candidates that can be selected based on the adaptive frequency hopping scheme can be increased.

At this time, the reduction of the number of unit channels means compression of the used frequency bandwidth of the used wireless LAN channel. Usually, an unused frequency band is provided between the wireless LAN channel and the Bluetooth channel with an allowance for the number of unit channels. In many cases, the unused frequency band can be used effectively.
Also, in the wireless LAN communication system, each wireless LAN channel has a wide frequency band with a width of 20 MHz centered on the carrier frequency, and even if radio wave interference with the Bluetooth channel occurs at the end, wireless LAN data Since the influence on communication is extremely small, the peripheral frequency band of the wireless LAN channel can be effectively used only in a severe wireless communication environment in the ISM band.

[Fifth Embodiment]
Next, a telephone control device according to a fifth embodiment of the present invention is described.
In the first embodiment, when the communication status confirmation means 15C confirms the radio communication status at the call terminal 2A using the radio communication channel, the number of call terminals is divided by the number of usable channels of the call terminal 2A. The case where it is determined that the wireless communication status is deteriorated based on the obtained communication status index has been described.

The communication quality that the user feels subjectively about the voice call depends on various factors such as individual variations for each user and variations depending on the contents and situations exchanged by the voice call.
In the present embodiment, in response to a user operation at the call terminal 2A, the communication status confirmation unit 15C determines that the wireless communication status is deteriorated, so that the wireless communication status is deteriorated according to the user's intention. It can be judged.

  That is, when the control unit 15 of the telephone control device 1 receives operation information indicating a predetermined user operation from the call terminal 2A via the extension transmission line 5, the communication status confirmation unit 15C performs wireless communication with the call terminal 2A. It is determined that the situation has deteriorated, and the used channel revision process of FIG. 5 is executed. The user operation at this time may be an operation indicating deterioration or improvement of the wireless communication status, an operation requesting an increase in the number of usable channels, or an operation instructing the start of a voice call. Also good.

  Accordingly, a part or all of the unusable channels set as unusable in the channel management information 14B of the call terminal 2A are set to be usable in any situation or timing according to the user's intention, and the call terminal The number of usable channels in 2A can be increased, and the communication quality that the user feels subjectively about the voice call can be improved in real time.

  When the communication status confirmation unit 15C determines that the wireless communication status has deteriorated in response to a user operation from the call terminal 2A, the call status information 15A refers to the call control information 14A in the storage unit 14 and The implementation of the voice call may be confirmed, and it may be determined that the wireless communication status has deteriorated according to the user operation only when the voice call at the call terminal 2A is started or during the call. As a result, unnecessary use channel revision processing can be avoided.

  Further, in the present embodiment, the case where it is determined that the wireless communication status is deteriorated when a user operation is detected is described as an example. However, the deterioration determination of the wireless communication status is not limited to this. Alternatively, other determination methods may be used.

For example, the communication status confirmation unit 15C may monitor whether or not a voice call is performed at the call terminal 2A, and may determine that the wireless communication status has deteriorated according to the detection of the voice call. At this time, the presence / absence of the voice call may be acquired from the call control information 14 </ b> A of the storage unit 14.
Thereby, it is possible to automatically increase the number of usable channels of the call terminal 2A almost simultaneously with the start of the voice call, and to suppress a decrease in communication quality due to the voice call.

[Extended embodiment]
In each of the above embodiments, the case where the wireless communication method used by the telephone terminal 2 is the Bluetooth wireless communication method has been described as an example. However, the present invention is not limited to this, and an adaptive frequency equivalent to the Bluetooth wireless communication method is used. As long as the wireless communication method uses the hopping method, each embodiment can be applied in the same manner as described above, and the same effect can be obtained.
In the third embodiment, the case where the wireless communication method used in combination with the Bluetooth wireless communication method in the same wireless area is a wireless LAN communication method is described as an example. However, the present invention is not limited to this. Even in other wireless communication systems, the third embodiment can be applied in the same manner as described above, and the same operational effects can be obtained.

  In each embodiment, the case where the streaming wireless communication is a voice call has been described as an example. However, the present invention is not limited to this. For example, the telephone terminal 2 receives video data from a communication network (not shown) via the communication line 10, and the video data is displayed on a display terminal (not shown) instead of the handset 3 connected via the wireless line 4. Even when performing video communication for playback, each embodiment can be applied in the same manner as described above, and even when the number of usable wireless communication channels is reduced, it is possible to suppress degradation in communication quality of video communication to some extent. Further improvement is also possible.

It is a block diagram which shows the structure of the telephone control apparatus concerning the 1st Embodiment of this invention, and its telephone system. It is a block diagram which shows the structure of the telephone terminal used with the telephone control apparatus concerning the 1st Embodiment of this invention. It is a structural example of the channel management information used with a telephone control apparatus. It is an example of a structure of the channel management information used with a telephone terminal. It is a flowchart which shows the use channel revision process of the telephone control apparatus concerning the 1st Embodiment of this invention. It is a flowchart which shows the channel release process of the telephone control apparatus concerning the 2nd Embodiment of this invention. It is a structural example of the channel management information used with the telephone control apparatus concerning the 3rd Embodiment of this invention. It is a structural example of the wireless LAN channel management information used with the telephone control apparatus concerning the 4th Embodiment of this invention. It is an example of a structure of a channel number conversion table. It is a flowchart which shows the channel release process of the telephone control apparatus concerning the 4th Embodiment of this invention. It is explanatory drawing which shows the operation example of a compression channel setting process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Telephone control apparatus, 10 ... Communication line, 11 ... External line I / F part, 12 ... Extension I / F part, 13 ... Switch part, 14 ... Memory | storage part, 14A ... Call control information, 14B ... Channel management information, 14C ... Wireless LAN channel management information, 15 ... Control unit, 15A ... Call control means, 15B ... Channel management means, 15C ... Communication status confirmation means, 15D ... Channel release means, 2 ... Telephone terminal, 2A ... Telephone terminal, 20 ... Extension I / F unit, 21 ... voice processing unit, 22 ... display unit, 23 ... operation input unit, 24 ... storage unit, 24A ... channel management information, 24P ... program, 25 ... control unit, 25A ... call control means, 25B ... Channel management means, 26 ... wireless module, 27 ... wireless transmission / reception section, 28 ... module control section, 28A ... communication control means, 29 ... module storage section, 29A ... channel table, 3 ... Han Set, 4 ... wireless line, 40 ... wireless LAN channel, 41 ... unusable channels, 42, 43 ... available channels, n, n '... Units channels, dn ... number of compressed channels.

Claims (1)

A plurality of telephone terminals connected to the handset via radio lines composed of a plurality of radio communication channels having different carrier frequencies, and connecting the communication lines from the communication network and accommodating the telephone terminals via an extension transmission path; A telephone control device that realizes a telephone call at the telephone terminal by exchanging connection between the telephone terminal and the communication line or between the telephone terminals, and the telephone terminal transmits the wireless communication channel between the telephone terminals. Channel management information indicating whether or not each wireless communication channel can be used in the telephone terminal, and sequentially switching and selecting at predetermined intervals from wireless communication channels set to be usable in the channel management information Wireless communication with the telephone terminal handset using the wireless communication channel, and the selected wireless communication Yaneru is a telephone control apparatus used when not available by interference in the telephone system to set the disabled use of the wireless communication channel to the channel management information,
A function of storing each channel management information acquired from each telephone terminal via the extension transmission path in a storage unit in association with the telephone terminal, and channel management information read from the storage unit in the extension transmission path A channel management means having a function to notify and set the telephone terminal via
A communication status confirmation means for confirming a wireless communication status at a call terminal that performs a call using the wireless communication channel among the telephone terminals;
When it is confirmed by the communication status confirmation means that the radio communication status at the call terminal has deteriorated, a part or all of the unavailable channels set as unavailable in the channel management information of the call terminal can be used. A channel opening means for updating , and
The channel opening means has at least one radio communication channel using a carrier frequency corresponding to a radio frequency band used in a radio communication scheme different from that of the call terminal when setting the unusable channel of the call terminal to be usable. A telephone control device characterized in that, when disabled by the channel management information, it is set to enabled in order from an unusable channel located at an end of the radio frequency band .

Images