JPH0549065A - Key telephone system - Google Patents

Abstract

PURPOSE:To provide the excellent key telephone system with low power consumption by operating effectively only a required extension telephone set so as to reducing electric energy of power consumption when the pushbutton telephone set is in operation with a few number of persons because of lots of unattendees on holidays or national holidays. CONSTITUTION:In the key telephone system comprising a master set C and plural extension telephone sets D1-Dn connecting to the master set C, each of the extension telephone sets D1-Dn is provided with a noise detection circuit 21 measuring a surrounding noise level for each prescribed time. Then the master set C is provided with a noise discrimination circuit 16 comparing the measured value obtained at the noise detection circuit 21 with a preset reference value so as to discriminate validity or invalidity of each extension telephone set, a function control circuit 17 controlling the function of the extension telephone set discriminated to be invalid and a power supply control circuit 18 controlling power supply to activate only a valid extension telephone set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button telephone apparatus having an extension telephone capable of making a call by connecting a plurality of telephones to one or two or more telephone lines, and reducing power consumption in the apparatus. This is related to power saving for

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional key telephone device, FIG. 5 is a partial detailed view of an extension telephone, and FIG. 6 is a flow chart for explaining the operation of the conventional key telephone device. 1
Is a terminal board connected to a telephone line, 2 is a line control circuit as a line control means for controlling connection and disconnection of the telephone line by connecting to the terminal board 1, and 3 is also connected to the terminal board 1. An extension control circuit 4 as extension control means for controlling connection and disconnection with an extension telephone set, which will be described later, serves as a main control unit that connects the line control circuit 2 and the extension control circuit 3 to the terminal board 1. The CPU is connected to a power source via the power source circuit 5, and thus constitutes the key telephone main unit A. B1 to Bn are the button telephone main unit A and the terminal board 1
The extension telephones are connected to each other through the key telephone main device A, and each of the extension telephones has the following configuration.

Reference numeral 6 denotes a hook switch, which is used for communication or transmission by putting on or taking off the handset, and for turning on / off the call state. Reference numeral 7 denotes a communication circuit, which is in a communication state when the hook switch 6 is off, that is, when the handset is detached from the extension telephone main body. An incoming call detection circuit 8 detects an incoming call from another telephone set (not shown) or another extension telephone set B via the key telephone main unit A.
On the contrary, a transmission circuit 10 for making a call from the extension telephone set B is a microphone provided in a handset for making a call. Reference numeral 11 is an incoming call control circuit for controlling the occurrence of an incoming call bell based on the detection result of the incoming call detection circuit 8, and 12
Is a ringing circuit that generates a bell etc. to notify the incoming call,
Reference numeral 13 is a speaker for generating an incoming call bell or the like. The extension telephone set B is configured by the above-mentioned configuration, and depending on the usage situation, a plurality of arbitrary units B1 to
Bn is connected.

Then, the plurality of extension telephones B1 to B
Each n is provided with a button 14 as shown in FIG. 4, and this button 14 has an LED 1 for displaying the usage status of the extension telephone B by turning on or off.
5 are provided corresponding to the respective buttons 14. Reference numeral 16 is a display label for displaying to the user which line the button 14 is connected to, and the user is provided with the LED 15 of the button 14 provided corresponding to the display label 16. Whether it is in use or not is determined by the blinking state of.

Next, the operation of the key telephone device having the above-mentioned configuration will be described with reference to the flowchart of FIG.
The symbol S shown below indicates a processing step. First,
In this key telephone device, the CPU 4 of the main device A constantly monitors the states of all the extension telephones B1 to Bn (S1). Then, in the line control circuit 2 of the main device A, another external telephone or extension telephone B is connected via a telephone line.
It is determined whether or not the communication signals from 1 to Bn are received (S2), and if it is determined that the communication signal is not received, the extension telephone set B
The extension control circuit 3 determines whether or not the call is originated from any one of 1 to Bn depending on whether or not the hook switch 6 of the extension telephone set B is turned off and the dial number of the other party is transmitted. S3). When it is determined in S3 that the extension telephone numbers B1 to Bn have not transmitted the dial number and the calling state is not established, the process returns to S1 again.

When a call from one of the extension telephones B1 to Bn (a plurality of telephones is possible) is confirmed in S3,
The extension telephones transmitted by the extension control circuit 3 are set to B1 to Bn.
More specific confirmation is performed (S4). The information determined by the line control circuit 2 and the extension control circuit 3 is stored in the CPU.
4, the CPU 4 sends all the terminals B1 to B of the extension telephone B.
In order to notify the user of the usage status of the line and the usage status of the extension, a lighting instruction is given to the n so that the extension telephones B1 to Bn match the display number of the display label 16 indicating the line number being used. LED15 of button 14
Is turned on (S5). In addition, at the extension telephone B which is transmitting at this time and the extension telephone B which is not transmitting, the LED 15
They are distinguished by different lighting colors, blinking conditions, and so on.

Then, the dial number sent from the transmission circuit 9 of the extension telephone set B is called to the other party through the extension control circuit 3, CPU 4 and line control circuit 2 of the key telephone main unit A (S6). The line control circuit 2 judges the incoming call of the other party depending on whether the hook switch of the other party of communication is in the off state, that is, whether the handset is detached (S7). Here, when it is determined that the other party has received a call, the extension telephones B1 to Bn that have sent the call are sent to the CPU 4 and the extension control circuit 3
The caller is connected to the other party through the call, and the caller terminal and the callee party are in a call state (S8). If the call is received by the other party in S7, that is, if the hook switch remains in the on state without being turned off, the process returns to S6 to continue calling the other party.

After this, it is judged whether the hook switch 6 of either the sender or the receiver is in the on state, that is, whether or not the detached handset is attached to the telephone body (S9). If it is not turned on, the call is continued, and if it is determined that it is on, the extension control circuit 3 instructs the CPU 4 and the line control circuit 2 to end the call, and the call is ended (S10). When the call ends in this way, the line control circuit 2 releases the line being communicated (S11), and the CPU 4 issues an instruction to turn off the LED 15 of the button 14 of the extension telephone set B corresponding to the opened line to the extension telephone set B. Instruct all terminals B1 to Bn,
When all the extension telephones B1 to Bn turn off the LED 15 (S
12), which completes the operation.

Further, in S2, when an outgoing signal from another telephone is received, it is determined that the incoming call is received, and the line control circuit 2 confirms the incoming line (S13). CPU
L of extension telephone B corresponding to the line number received by 4
The ED 15 is instructed to be turned on, and all the terminals B1 to Bn of the extension telephone set B are instructed to generate a ring tone (S14). As a result, the incoming call detection circuit 8 and the incoming call control circuit 11 of the extension telephone set B passing through the extension line control circuit 3 send out the ringing tone from the speaker 13 through the ringing circuit 12 and turn on the LED 15 to turn on the LED 15. A ringing tone from the speaker 13 is used to notify the user that an incoming call has been received, and the LED 15 is turned on to indicate from which line the incoming call came (S15).

The user who confirms the incoming call by this display picks up the handset of the corresponding extension telephone set B to turn off the hook switch 6 or to turn on the LED.
It is determined whether or not the incoming call is confirmed by the extension control circuit 3 by pressing the button 14 corresponding to 15 (S16). When an incoming call is confirmed in S16, the CPU 4 connects the line of the line control circuit 2 and the extension of the extension control circuit 3 to establish a call state (S).
17). If the incoming call is not confirmed while the hook switch 6 remains on in S16, the process returns to S15 and the LED
Lighting of 15 and the ringing tone from the speaker 13, that is, the ringing tone is continued.

In this way, after the call is established, the hook switch 6 of either the caller or the callee is in the on state, that is, the detached handset is attached to the telephone body or is pressed. It is judged whether or not it has been returned to the original state by pressing the button 14 again (S1
8) If the hook switch 6 is not turned on here, the process returns to S17 to continue the call. If it is determined that the call is on, the process proceeds to S10, and so on until the operation ends. .. In this way, when the key telephone main unit A confirms the incoming call, all the terminals B1 to Bn of the extension telephone set B are instructed to notify the incoming call, that is, the LED 15 is turned on and the speaker 13 is called. A sound is sent to notify the user, and any of the handsets B1 to Bn picks up the handset or presses the button 14 to urge a call.

[0012]

However, in the above-mentioned conventional technique, among extension telephones installed in a plurality, not all those who use these are present, and there are cases where they are absent. .. That is, when the power of the key telephone main unit A cannot be turned off even on holidays and public holidays, for example, when only a few people need an extension telephone, The power cannot be turned off. Therefore, if the key telephone main unit A is turned on, even if it is known that it is unnecessary, all the extension telephone terminals must be operated in a full operating state, and the status of all extension telephone terminals is constantly monitored. , The status is displayed, and the ringing tone is sent to enable all terminals regardless of the presence / absence of the user.
There is a problem in that it is not possible to reduce the electric power energy in the operating cost of the button telephone device.

The present invention has been made to solve the above-mentioned problems, and there are many absentees such as holidays and public holidays, and power consumption is reduced when only a small number of people operate the key telephone device. It is an object of the present invention to realize a reduction by effectively operating only necessary extension telephones and to provide an excellent key telephone device with low power consumption.

[0014]

In order to achieve the above object, the present invention provides a line control circuit which is connected to a telephone line and controls this line, and a control of a plurality of extension telephones connected to this line. A main device having an extension control circuit for controlling and a main control unit for controlling these, and a power supply circuit for connecting to a power supply, and a main device connected to the main device for attaching / detaching a handset or pressing a button Equipped with a hook switch that disconnects the line by performing a call, a display unit that notifies the user of an incoming or outgoing call from another telephone line, and a call circuit that makes a call. When the line control circuit of the main unit confirms the incoming call or the extension control circuit confirms the outgoing call, the control unit operates the display means of the extension telephone set. In a button telephone device that informs of an incoming or outgoing call, and the hook switch of the called party is turned off by this notification to enable a call between the calling party and the called party, first, for each extension telephone, Provide a noise detection circuit that measures the ambient noise level every predetermined time. Then, in the main device, the measured value of the noise level for each extension telephone obtained by the noise detection circuit,
A noise judgment circuit for judging validity or invalidity of each extension telephone by comparing with a preset reference value, and a first number for accommodating the terminal number of the extension telephone which is judged invalid by the noise determination circuit. A function control means for providing a memory and a second memory for accommodating the terminal number of the extension telephone determined to be valid by the noise determination circuit, and for controlling the function of the invalid extension telephone accommodated in the first memory And a power supply control means for controlling the amount of power supply to the invalid extension telephones, and the valid and invalid settings of the extension telephones are determined based on the noise level of all extension telephones measured at predetermined intervals. This is done every hour so that only the extension telephones that are determined to be valid are always operated.

[0015]

In the above-mentioned structure, when the operation of the key telephone device is started, first, the noise level of all terminals of the extension telephone is measured by the noise detection circuit according to the instruction of the main control section of the main device, and this is measured by the main device. It is transmitted to the noise determination circuit, where it is compared with a previously stored reference value. If the noise judging circuit judges that the measured value is equal to or smaller than the reference value, the terminal is stored in the first memory, and if it is judged that the measured value is larger than the reference value, the terminal number is judged. 2 memory. In this way, the measured values of all extension telephones are sequentially compared, and when all the terminal numbers are stored in either the first or second memory, the extension telephone D having the terminal number stored in the first memory is All invalid terminals are set to L from the function control circuit for this invalid terminal.
While stopping the lighting of the ED and the sound of the speaker,
The power supply control circuit reduces the power supply. Further, the terminal stored in the second memory is an effective terminal, that is, the power is supplied, and the LED control and the sound generation by the speaker are controlled. Thus, after the initial setting of the effective terminal, the operation is started, and only the extension telephone D of the effective terminal set by the setting operation of the effective terminal is operated. Further, the setting operation of this effective terminal is set to be performed at a predetermined interval, for example, every 30 seconds after the start of operation and no incoming call or outgoing call is detected, and the latest effective terminal is always set. I try to understand the setting information of.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a key telephone device, FIG. 2 is an operation flowchart for determining an effective terminal of an extension telephone, and FIG. 3 is a flowchart explaining an operation of the key telephone device. In FIG. 1, 1 is a terminal board, 2 is a line control circuit, 3 is an extension control circuit, 4 is a CPU, 5 is a power supply circuit,
6 is a hook switch, 7 is a call circuit, 8 is an incoming call detection circuit, 9 is an outgoing circuit, 10 is a microphone, 11 is an incoming call control circuit, 12 is a sounding circuit, and 13 is a speaker. Since it is almost the same as the above, the same reference numerals as the conventional ones are attached and the description thereof is omitted. In addition, the main unit of the key telephone device that controls the supply of power will be described as C, and the plurality of extension telephones connected thereto will be described as D1 to Dn.

Reference numeral 16 is a noise determination circuit provided in the main unit C by being connected to the extension control circuit 3 and the CPU 4, and the noise level detected from the surroundings of all the extension telephones D1 to Dn is absent by the user. The background noise value X, which is a reference value for determining that it is, is preset and stored, and compared with the stored background noise value X, and all the extension telephones D1 to Dn Determine if there are no people around. Reference numeral 17 is a function control circuit provided in connection with the noise determination circuit 16 and controls the functions of the corresponding extension telephones D1 to Dn based on the determination result obtained from the noise determination circuit 16. That is, when it is determined that there is no person around any one or several of the extension telephones D1 to Dn, the LED of the corresponding extension telephone D is turned on, the ringing sound is generated by the speaker 13, and the like. To stop.

A power supply control circuit 18 controls the supply of power to the corresponding extension telephones D1 to Dn based on the determination result obtained from the noise determination circuit 16. Reference numeral 19 denotes a first memory connected to the extension control circuit 3, and the noise determination circuit 16 determines that the noise level of a person in the vicinity is less than or equal to the background noise value X which is a reference value, that is, there is no person in the vicinity. The stored extension number of the extension telephone D is stored. Also,
Reference numeral 20 is a second memory which is also connected to the extension control circuit 3, and the noise determination circuit 16 determines that the noise level of the surrounding people is higher than the background noise value X which is the reference value, that is, that there is a person in the surroundings. The extension number of the extension telephone D is accommodated. Reference numeral 21 denotes a noise detection circuit provided in each of the extension telephones D1 to Dn, which measures the ambient noise level An with the microphone 10, and the noise level An as the measured value is used as the main device C. It is transmitted to the noise determination circuit 16 via the extension control circuit 3.

The operation of the key telephone device having the above-described structure will be described with reference to the flow charts of FIGS. 2 and 3 below. First, an operation flowchart of effective extension telephone setting will be described with reference to FIG. The symbols SA and S shown below
B indicates a processing step. When the power is turned on to start the operation of the key telephone device, the CPU 4 of the main device C measures the ambient noise level An by the noise detection circuit 21 and the microphone 10 in all the terminals D1 to Dn of the extension telephone D. (SA1). The measured noise level An of the extension telephone D is transmitted to the noise determination circuit 16 of the main device C through the extension control circuit 3, and the background noise value X as a reference value stored in advance in the noise determination circuit 16 is used. Compare (SA2).

When it is judged that the noise level An of the extension telephone D measured at SA2 is equal to or smaller than the background noise value X, the terminal number is stored in the first memory 19 of the extension control circuit 3. (SA3), again
If it is determined that the background noise value is larger than the background noise value X, the terminal number is stored in the second memory 20 of the extension control circuit 3 (S
A4). In this way, the noise levels An of all the extension telephones D1 to Dn are sequentially compared, and this operation is repeated until all the terminal numbers are stored in either the first or second memories 19 and 20 (SA5).

Of the terminal numbers all stored in the first memory 19 and the second memory 20, the first memory 1
All the extension telephones D having the terminal numbers stored in 9 are set as invalid terminals (SA6). Next, with respect to the extension telephone D determined to be an invalid terminal in SA6, the function control circuit 17 stops the lighting of the LED and the sounding of the speaker 13 (SA7). Then, the power supply control circuit 18
The power supply to the extension telephone D which is determined to be invalid by is reduced (SA8), the extension telephone D having the terminal number stored in the second memory 20 is used as a valid terminal, that is, the power is supplied and the LED Control of lighting and extinguishing of lights, and control of generation of sound by speaker (SA
8). When the initial setting of the valid terminal is performed in this manner, the key telephone device can be operated. The following is a flowchart after the operation of the key telephone device is started.

FIG. 3 is a flow chart of the operation of the key telephone device after the initial setting of the valid terminal which needs to control the LED and the speaker and the invalid terminal which does not require the control and the power supply is reduced. Is. Note that this operation flowchart is basically similar to the operation described in the related art, but when the line control circuit 2 or the extension control circuit 3 confirms that an incoming call or an outgoing call is made, the user is notified of this. Extension telephones D1 to D
When controlling the n LED and the speaker, in the present embodiment, only the extension telephone D of the valid terminal set by the setting operation of the valid terminal described above is operated. Furthermore, the setting operation of this effective terminal is performed at a predetermined interval, for example, 3 when no incoming or outgoing call is detected.
It is set to be performed every 0 seconds so that the latest setting information of the valid terminal is always grasped.

In FIG. 3, the key telephone device first performs the above-mentioned valid terminal setting operation (SB1), and only the extension telephone set valid here has its state changed to the CP of the main device C.
It is constantly monitored by U4 (SB2). Then, in the line control circuit 2 of the main device C, it is judged whether or not there is an incoming call (SB3), and if it is judged that there is no incoming call, then among the extension telephones D1 to Dn, It is judged by the extension control circuit 3 whether or not the call is originated from any one (S
B4) If it is determined in SB4 that no extension number D1 to Dn has transmitted a dial number and the call is not in a calling state, the process returns to S1 to repeat the valid terminal setting operation. As described above, this setting operation is performed every predetermined time, for example, at intervals of 30 seconds in a situation where neither incoming call nor outgoing call is detected, so that the latest valid terminal status is always set.

When a call from any one of the extension telephones D1 to Dn (a plurality of the extension telephones is possible) is confirmed in SB4, the extension control circuit 3 identifies the extension telephones that are calling from all the terminals D1 to Dn. After confirming (SB5) and sending it to the CPU 4, the CPU 4 informs the user of the usage status of this line and the usage status of the extension only to the valid terminals of the extension telephones D1 to Dn which are determined to be valid at SB1. In response, a lighting instruction is issued to display the LED, and the valid terminal receiving the instruction turns on the LED of the button that matches the display number of the display label displaying the line number in use (SB
6). It should be noted that it is the same as in the prior art that the extension telephone D that is transmitting at this time and the extension telephone D that is not transmitting are distinguished by differentiating the lighting color of the LED, the blinking condition, and the like.

Then, the dial number transmitted from the transmission circuit 9 of the extension telephone Dn of the transmission source confirmed in SB4 is called to the other party through the extension control circuit 3, CPU 4, and line control circuit 2 of the main unit C ( SB7) When the line control circuit 2 confirms the incoming call of the other party (SB
8) The originating extension telephone D is connected to the other party via the CPU 4 and the extension control circuit 3, and the originator terminal and the other party of the destination become in a call state (SB9). Also, the SB
If the incoming call of the other party is not confirmed at 8, the process returns to SB7 and the calling of the other party is continued.

The operation after this is the same as the conventional one, and the hook switch 6 for either the sender or the receiver is used.
Is on, that is, it is determined whether or not the detached handset is attached to the telephone body or the button is pressed again (SB10), and if the hook switch 6 is not on, the call continues, and If it is determined to be on, the call ends (SB11). When the call ends, the line control circuit 2 releases the line that was communicating (SB
12), the CPU 4 instructs all terminals D1 to Dn to turn off the LED of the extension telephone D corresponding to the opened line,
All extension telephones D1 to Dn turn off the LED (SB1
3) Then, the operation ends.

When it is determined in SB3 that there is an incoming call from another telephone, the line control circuit 2 checks the incoming line (SB14), and the CPU 4 turns on the LED of the extension telephone D corresponding to the incoming line number. At the same time as instructing, the ring tone generation is instructed only to the valid terminals of the extension telephones D1 to Dn which are determined to be valid terminals in SB1 (SB15). As a result, the effective terminal is instructed to output the ringing tone by the speaker 13 and turn on the LED via the ringing detection circuit 8, the ringing control circuit 11, and the ringing circuit 12 of the extension telephone D. Inform the person. At this time, the line from which the call came is notified by turning on the LED (SB16).

The user who confirms the incoming call by this display picks up the handset of the extension telephone D and turns off the hook switch 6 or presses the button corresponding to the LED 15 which is lit to control the extension line. It is determined whether or not the incoming call is confirmed by the circuit 3 (SB17).
When the incoming call is confirmed, the CPU 4 connects the line of the line control circuit 2 and the extension of the extension control circuit 3, whereby the call is established (SB18). If the incoming call is not confirmed while the hook switch 6 remains on in SB17, the SB switch
Returning to 16, the lighting of the LED and the ringing tone from the speaker, that is, the ringing tone is continued.

In this way, after the call is established, the hook switch 6 of either the caller or the callee is in the on state, that is, the detached handset is attached to the telephone body or is pressed. It is judged whether or not it has been returned to the original state by pressing the button 14 again (SB1
9) Here, if the hook switch 6 is not turned on, the process returns to SB18 to continue the call. If it is determined that the hook switch 6 is turned on, the process proceeds to SB11, and so on until the operation ends. ..

As described above, in the main unit C, the effective terminal setting operation for setting that the user is seated in the vicinity and needs to be operated is performed at predetermined intervals to obtain the latest effective terminal. The terminal is always measured and set, and an instruction for notifying that each of the terminals D1 to Dn of the extension telephone set D which is set to be valid is informed that the incoming call or the outgoing call is made, that is, The LED is turned on and a ringing tone is sent by a speaker to notify the user, and the user is prompted to pick up one of the handsets of the extension telephone D or press a button to talk.

[0031]

As described above, according to the present invention, a main device and a plurality of extension telephones connected to the main device are provided, and when an incoming or outgoing call is confirmed in the main device, In the button telephone device that operates the display means of the extension telephone by the control of the device to notify the user that an incoming or outgoing call has been made, and by this notification, when the hook switch of the incoming call destination is turned off, the call becomes possible.
Each of the extension telephones is provided with a noise detection circuit that measures the noise level around the extension telephones at predetermined time intervals.

Further, the main unit is provided with the measured value of the noise level for each extension telephone set obtained by the noise detection circuit.
A noise judgment circuit for comparing with a preset reference value is provided, and the first memory for storing the terminal number of the extension telephone, which is judged to be equal to or smaller than the reference value by the noise judgment circuit, and the reference value A second memory for storing the terminal number of the extension telephone set determined to be large is provided, and the extension telephone set stored in the first memory is set invalid and the extension telephone set stored in the second memory is set valid. The extension telephone set is provided with a function control unit for controlling the function of the extension telephone set as invalid and a power supply control unit for controlling the amount of power supply to the extension telephone set as invalid. The valid and invalid settings of are set every predetermined time based on the noise level of all extension telephones measured every predetermined time so that only the extension telephones that are judged to be valid are always operated. That.

For this reason, since the extension telephone set which is determined to be ineffective reduces the power supply and the function control, the wasteful consumption of electricity is suppressed when the absence of the user is known to the user. It is possible to provide an excellent key telephone device that reduces power consumption by effectively supplying the power and controlling the function by supplying the power and controlling the function only to the valid extension phones whose presence is confirmed.

[Brief description of drawings]

FIG. 1 is a block diagram of a key telephone device.

FIG. 2 is a flowchart of a setting operation of an effective terminal of an extension telephone.

FIG. 3 is an operation flowchart of a key telephone device.

FIG. 4 is a block diagram of a conventional key telephone device.

FIG. 5 is a partial detailed view of an extension telephone.

FIG. 6 is a flowchart illustrating the operation of a conventional key telephone device.

[Explanation of symbols]

 2 line control circuit 3 extension control circuit 4 CPU 6 hook switch 13 speaker 16 noise determination circuit 17 function control circuit 18 power supply control circuit 19 first memory 20 second memory 21 noise detection circuit C main device D extension telephone

Claims (1)

[Claims] 1. A main control for controlling a line control means connected to a telephone line for controlling the line, and an extension control means for controlling a plurality of extension telephones connected to the line. Unit and a power supply circuit for connecting to a power supply, and a hook switch connected to the main device for disconnecting the line by attaching / detaching a handset or pressing a button, etc. When the incoming or outgoing call from the telephone line is confirmed, it comprises a plurality of extension telephones having a display means for notifying the user of this and a call circuit for making a call, and the line of the main device When the control unit confirms the incoming call or the extension control unit confirms the outgoing call, the control unit operates the display unit of the extension telephone to notify the incoming call or the outgoing call. In a key telephone device that enables a call between a caller and a callee by turning off a hook switch, in each of the extension telephones, noise detection means for measuring a noise level around the extension telephones at predetermined time intervals. The main device is provided with a valid or invalid value for each extension telephone by comparing the measured value of the noise level for each extension telephone obtained by the noise detection means with a preset reference value. Noise determining means, a first memory for accommodating the terminal number of the extension telephone set determined to be invalid by the noise determination means, and a terminal number of the extension telephone set determined to be valid by the noise determination means A second memory; a function control means for controlling the function of the invalid extension telephone housed in the first memory; and a power supply amount for the invalid extension telephone. A power supply control means for controlling the extension telephone set is provided to enable and disable the extension telephone set at every predetermined time based on the noise level of all extension telephones measured at every predetermined time. A button telephone device characterized in that only one is always operated.