JPH05344054A - Wireless telephone set - Google Patents

Abstract

PURPOSE:To attain paging or interrupt talking to a busy slave set in the cordless telephone set. CONSTITUTION:A slave set 1 is provided with a page key 152, a generating circuit 161 generating a control signal SPG for a frequency at the outside of a band of a voice signal when the page key 152 is operated, and a detection circuit 162 detecting the control signal SPG. A master set is provided with a similar page key, a similar generating circuit and a similar detection circuit. When the slave set 1 is connected to an external line through the master set and the page key of the master set is operated, the control signal SPG representing the operation is sent from the master set to the slave set 1 together with a voice signal from an external line. When the page key 152 is operated in the slave set 1 for the transmission, it is noticed from the slave set 1 to the master set by the control signal SPG. Upon the receipt of a notice from the slave set 1, the master set holds the external line and makes connection for talking with the slave set 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone having extended functions.

[0002]

2. Description of the Related Art As a cordless telephone, there is one in which a plurality of cordless handsets can be used for one parent device. Then, in a cordless telephone that can use a plurality of cordless handsets, further, from one cordless handset to another cordless handset,
Some are capable of paging (a function that sounds a ringing tone, like a pager), and some are capable of calling between handset units.

[0003]

However, when the child device (or the parent device) is talking to an outside line, another child device may be added to the calling child device for the purpose of privacy protection. Paging and call interruption (call waiting function) cannot be performed from the device (or base device).

Therefore, even when the user of the other handset wants to call the outside line in a hurry, or when the user of the handset that is in the call has an errand, etc. I couldn't urge the handset to end the call early, so I just had to wait for the call to end.

The present invention solves such a problem,
It is for enabling a paging or a call from another child device to a child device that is in a call.

[0006]

Therefore, in the present invention, when the reference numerals of the respective parts are made to correspond to the embodiments described later, the page key 15 is assigned to each of the slave unit 1 and the master unit 2.
2, 252, and forming circuits 161, 261 that form a control signal SPG having a frequency outside the band of the voice signal when the page keys 152, 252 are operated, and the control signal SPG together with the voice signal of the call. 1, transmission circuits 115 and 215, and detection circuits 162 and 262 that detect the control signal SPG when the control signal SPG is transmitted from the other device 2 or 1. And the child machine 1 is the parent machine 2
When the page key 252 of the main unit 2 is operated when the page key 252 is connected to the outside line 3 through
When the page key 152 is operated in the handset 1 in response to the transmission, the control signal SPG indicating that the handset has been operated is transmitted together with the audio signal from the outside line 3 to the handset 1. The fact that the page key 152 has been operated is notified from the handset unit 1 to the base unit 2 by the control signal SPG,
When the base unit 2 detects the notification from the handset unit 1, it holds the outside line 3 and makes a connection for a call between the base unit 2 and the handset unit 1.

[0007]

When the page key 252 of the base unit 2 is operated even when the handset 1 is talking to the outside line 3, the handset 1 is notified of this. Therefore, when the page key 152 of the slave unit 1 is operated, this is notified to the master unit 2, the outside line 3 is held, and an extension call between the master unit 2 and the slave unit 1 is enabled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2, reference numeral 1 is a slave unit, 2 is a master unit, and 3 is a telephone line (external line). However, the cordless handset 1
1 illustrates an arbitrary one of the plurality of slaves 1A to 1N used in combination with the master 2. further,
In FIGS. 1 and 2 and the following description, only the portion related to the present invention is shown and described.
Since general operations such as a call from the master unit 2 and an incoming call from the slave unit 1 and the master unit 2 and a configuration therefor are the same as those in the related art, illustration and description thereof will be omitted.

In the handset 1, 100 is a transmission / reception antenna, 111 to 115 are transmission systems, 111 is a transmitter, 113 is a voice band, for example, a band pass filter having a pass band in the frequency band of 300 to 3400 Hz. , 115 is F
It is a transmission circuit including an M modulation circuit and a transmission amplifier. Further, reference numerals 121 to 124 denote a receiving system, 121 denotes a receiving circuit including a high frequency amplifier to an FM demodulating circuit, 1
22 is a bandpass filter having a voice band as a pass band,
Reference numeral 124 is a receiver.

Further, reference numeral 140 denotes a system control microcomputer, which controls the transmission circuit 115, the reception circuit 121 and the like to realize various operations, and is a part of a processing routine. For example, the sequences 300 and 40 shown in FIGS.
It has a routine that executes 0. The lower side of FIG. 4 is followed by the upper side of FIG.

Although not shown, the memory of the microcomputer 140 stores a slave code HSID indicating which of the slaves 1A to 1N the slave 1 is.
Then, a command signal CMND indicating a request for various processing is transmitted and received between the child device 1 or the parent device 2, and the child device code HSID is the command signal CMND if necessary.
Sent and received by.

When the handset device 1 receives the handset device code HSID, the handset device 1 checks whether the handset device code HSID matches the handset device code HSID stored in the handset device. The signal CMND is validated and the process according to the command signal CMND is executed. When they do not match, the command signal CMND is invalidated and ignored.

Further, 151 is a dial key, 152 is various operation keys, 159 is a ringer for notifying an incoming call, 1
Reference numeral 61 is a paging signal forming circuit, and 162 is a paging signal detecting circuit. In this case, the paging signal SPG formed in the forming circuit 161 has a frequency that can be transmitted and received at a frequency outside the voice band, for example, 4 kHz, and is pulse-modulated according to the data (telegram) from the microcomputer 140. ..

On the other hand, the master unit 2 has a circuit similar to that of the slave unit 1, and the circuit corresponding to the circuit of the slave unit 1 has 100 circuits.
The reference numerals of 200s are used instead of the numbers, and the description is omitted. However, this base unit 2 has two sets of transmission circuits 215, 2
16 and receiving circuits 221 and 226. Also, 22
Reference numeral 5 is a switch circuit, and this switch circuit 225 switches the audio signals to be accessed by the transmission circuits 215 and 216 and the reception circuits 221 and 226. further,
230 is an NCU.

Call between the cordless handset and an outside line This is a general call in a cordless telephone,
That is, this is a case where the cordless handset 1 is used to make a call with an outside line.

That is, during a call between the handset 1 and an outside line,
The voice signal ST from the transmitter 111 is supplied to the transmission circuit 115 through the signal line of the amplifier 112, the band pass filter 113, and the addition circuit 114, and is converted into the FM signal SU of the up channel, and this FM signal SU is transmitted to the antenna 100. And is transmitted to the base unit 2.

Then, in the master unit 2, the F from the slave unit 1
The M signal SU is received by the antenna 200 and is supplied to the receiving circuit 221, and the original audio signal ST is extracted from the receiving circuit 221, and this audio signal ST is converted into the switch circuit 225 → bandpass filter 222 → amplifier 223.
→ Sent to the line 3 through the signal line of the NCU 230.

The voice signal SR of the other party from the line 3
Is supplied to the transmission circuit 215 through the signal line of NCU 230 → amplifier 212 → band pass filter 213 → addition circuit 214 → switch circuit 225 and is converted into the FM signal SD of the downlink channel, and this FM signal SD is supplied to the antenna 200. Is transmitted to the child device 1.

Then, in the slave unit 1, F from the master unit 2
The M signal SD is received by the antenna 100 and supplied to the receiving circuit 121, the original audio signal SR is extracted from the receiving circuit 121, and this audio signal SR is passed through the signal line of the bandpass filter 122 → the amplifier 123. It is supplied to the handset 124.

Therefore, the user of the cordless handset 1 can talk with the other party of the outside line through the master unit 2.

An extension call from the master unit during a call between the slave unit and an external line. This is a call from the master unit 2 to the slave unit 1 during a call between the slave unit 1 and an outside line.
This is a case where when an extension call request is made to the outside line, the outside line is put on hold and extension calls can be made between the handset 1 and the base unit 2. And
This is performed, for example, like the sequence 300.

That is, according to the above, the slave unit 1 becomes the master unit 2
When a call is being made to an outside line through the telephone (step 301), the page key of the operation keys 252 of the base unit 2 is pressed. Then, the formation circuit 261 is formed by the microcomputer 240.
Is controlled to form a paging signal SPG of a telegram indicating "request for extension call", and this signal SPG is added to the adder circuit 214.
Is supplied to. Therefore, this paging signal SPG
Is transmitted to the handset 1 together with the voice signal SR during the call (step 311).

In the slave unit 1, the receiving circuit 12
1, the audio signal SR and the paging signal SPG are extracted, and these signals SR and SPG are the band pass filter 1
22 and the detection circuit 162. In this way, the audio signal SR is supplied to the amplifier 123 through the bandpass filter 122 and the call with the outside line is continued, but the paging signal SPG is extracted from the detection circuit 162.
The extracted paging signal SPG is used by the microcomputer 14
0 is supplied.

Then, the microcomputer 140 interprets the paging signal SPG and, in this case, indicates "extension call request". Therefore, the forming circuit 161 is controlled by the microcomputer 140 and "response to extension call request". "
Is generated, and the signal SPG is supplied to the adder circuit 114. Therefore, the paging signal SPG is transmitted to the base unit 2 together with the voice signal ST during the call (step 312).

Then, in the base unit 2, the receiving circuit 22
1, the audio signal ST and the paging signal SPG are taken out, and these signals ST and SPG are supplied to the bandpass filter 222 and the detection circuit 262 through the switch circuit 225. In this way, the audio signal ST is supplied to the amplifier 223 through the bandpass filter 222 and the call is continued, but the paging signal S is output from the detection circuit 262.
PG is extracted, and the extracted paging signal SPG
Are supplied to the microcomputer 240.

Then, the microcomputer 240 interprets the paging signal SPG and, in this case, indicates "response to request for extension call".
By this, the forming circuit 261 is controlled to form a paging signal SPG of a telegram indicating "drive of ringer".
PG is supplied to the adder circuit 214. Therefore, this paging signal SPG, together with the voice signal SR during the call,
It is transmitted to the child device 1 (step 313).

Therefore, in the handset 1, the detection circuit 162 supplies the microcomputer 140 with the paging signal SPG, which is a message indicating "drive the ringer".
When PG is supplied, the ringer 159 is activated by the microcomputer 140.
Is controlled, and thereafter, the ringer 159 outputs a ringer sound requesting an extension call.

Then, after that, between the base unit 2 and the handset unit 1, "extension call request" in steps 311 to 313,
The paging signal SPG of the message indicating "response to extension call request" and "ringer drive" is repeatedly accessed. At this time, since the paging signal SPG is outside the band of the voice signals ST and SR, it does not affect the communication between the handset 1 and the outside line. Also, although the ringer 159 is ringing, since the transmission and reception of the voice signals ST and SR between the handset 1 and the base unit 2 are being continued, it is necessary to keep talking between the handset 1 and the outside line. You can

However, since the ringer requesting an extension call sounds in the handset 1, the user of the handset 1 informs the other party of the outside line that the call is to be held temporarily, and then the handset 1
When the page key of the operation keys 152 is pressed, the microcomputer 140 turns off the ringer 159.

Further, when the page key is pressed, the forming circuit 161 is controlled by the microcomputer 140 to form a paging signal SPG of a message indicating "page key input", and this paging signal SPG is transmitted to the master unit 2. (Step 321).

Then, in the master unit 2, the paging signal SPG of a message indicating this "page key input" is supplied to the microcomputer 240. When this signal SPG is supplied,
The forming circuit 261 is controlled by the microcomputer 240 to form a paging signal SPG of a message indicating "response to page key input", and the paging signal SPG is transmitted to the child device 1 (step 322).

Then, in the handset 1, the paging signal S of the electronic message indicating the "response to page key input" is sent.
The PG is supplied to the microcomputer 140, and when the signal SPG is supplied, the forming circuit 161 is controlled by the microcomputer 140 and the paging signal S of a telegram indicating "holding of outside line".
A PG is formed, and this paging signal SPG is transmitted to the parent device 2 (step 323).

Then, in the base unit 2, the paging signal SPG of the electronic message indicating "holding the outside line" is sent to the microcomputer 24.
0 is supplied to the NCU 23 by the microcomputer 240.
The line 3 is put on hold by controlling 0, and the transmitter 211 and the receiver 224 are connected to the amplifiers 212 and 223 through the NCU 230.

Therefore, after that, if the user of the base unit 2 takes off the hooks of the handsets 211 and 224,
It becomes possible to make an extension call with the user of the cordless handset 1 by using 224 (step 331). For the extension call at this time, the channel used for the call between the handset 1 and the outside line is used as it is without interruption.

When the extension call between the base unit 2 and the handset unit 1 is completed, the user of the base unit 2 sends and receives the handsets 211, 22.
4 on the main unit 2 on-hook, this is the microcomputer 24
0, and the formation circuit 26 is generated by the microcomputer 240.
1 is controlled to form a paging signal SPG of a telegram indicating "end of extension call", and the paging signal SPG is transmitted to the handset 1 (step 341).

Then, in the handset 1, the paging signal SPG of the electronic message indicating "end of extension call" is supplied to the microcomputer 140. Then, the forming circuit 161 is controlled to indicate "release of hold". Message paging signal SPG
Is formed, and this paging signal SPG is transmitted to the base unit 2 (step 342).

The paging signal SPG is transmitted to the base unit 2
When it is received by the microcomputer 240 and supplied to the microcomputer 240, the microcomputer 240 controls the NCU 230 to release the hold of the line 3, and the line 3 is connected to the amplifiers 212 and 223 through the NCU 230. Therefore, thereafter, the user of the child device 1 and the partner of the outside line can resume the call through the parent device 2 (step 351).

Thus, in the present case, even if the handset 1 is talking to the partner of the outside line through the base unit 2, if the page key of the base unit 2 is pressed, the base unit 2 will extend the extension line to the handset 1. If the call request is notified and the handset 1 responds to the call, the outside line is held and the extension call can be made between the base 2 and the handset 1. When the extension call is finished, the call between the handset 1 and the outside line can be resumed.

This is an extension call between the slaves 1A and the outside line during the call between the slaves 1A and the outside line during the call between the slave 1A and the outside line. This is a case where the external line is put on hold when the request is made and an extension call can be made between the handset 1A and the handset 1B. Then, this is executed as in the sequence 400, for example.

That is, according to the above, any slave unit 1A
Is in a state of communicating with an outside line through the master unit 2 (step 401), the operation key 1 of another arbitrary slave unit 1B.
Press the page key out of 52. Then, the microcomputer 140 of the handset 1B forms a command signal CMND of a telegram indicating "request for extension call", and this signal CMND is transmitted to the transmission circuit 1
It is supplied to 15 and transmitted to the master unit 2 by the FM signal SU of the upstream channel (step 411). At this time, the channel of the FM signal SU is
The channel used between A and the base unit 2 is different.

Then, in the base unit 2, the receiving circuit 22
From 6, the command signal CMND from the slave unit 1B is taken out, and this signal CMND is supplied to the microcomputer 240. Then, the command signal CMND is interpreted by the microcomputer 240, and in this case, it indicates "extension call request". Therefore, the microcomputer 240 forms a command signal CMND of a message indicating "response to extension call request". Then, this signal CMND is supplied to the transmission circuit 216, converted into the FM signal SD of the downlink channel and transmitted to the handset 1B (step 412).

In the slave unit 1B, the receiving circuit 1
The command signal CMND is taken out from the microcomputer 21.
40. Then, in the microcomputer 140,
This command signal CMND is interpreted and, in this case, "response to request for extension call" is displayed.
A command signal CMND of a telegram indicating "confirmation of extension call" is formed by 40, and this signal CMND is supplied to the transmission circuit 115 and transmitted to the master device 2 (step 413).

Therefore, in the base unit 2, the command signal CMND of the electronic message indicating "confirmation of extension call" is taken out from the receiving circuit 226 and supplied to the microcomputer 240.
When this signal CMND is supplied, the slave unit 1A and the master unit 2 will be subsequently used.
Between steps 421 and 423, similar to steps 311 to 313 of sequence 300, using the currently busy channel. That is, the paging signal SPG, which is a telegram indicating “request for extension call”, “response to request for extension call”, and “drive ringer”, is repeatedly accessed between the slave unit 1A and the master unit 2.

When the master unit 2 first makes a "request for extension call" to the slave unit 1A, the ringer 159 is controlled by the microcomputer 140 in the slave unit 1A, and thereafter, the extension call is made from the ringer 159. The ringer sound requesting is output.

Since the ringer requesting the extension call is sounded in the handset 1A, the user of the handset 1A tells the other party of the outside line that the handset is on hold, and then the handset 1A is operated. If you press the page key of the key 152,
The ringer 159 is turned off by the microcomputer 140.

Further, when the page key is pressed, the forming circuit 161 is controlled by the microcomputer 140 to form a paging signal SPG of a message indicating "page key input", and this paging signal SPG is transmitted to the master unit 2. (Step 431).

Then, in the base unit 2, the paging signal SPG of a message indicating this "page key input" is supplied to the microcomputer 240. When this signal SPG is supplied,
The forming circuit 261 is controlled by the microcomputer 240 to form a paging signal SPG of a message indicating "response to page key input", and the paging signal SPG is transmitted to the slave unit 1A.
(Step 432).

In the slave unit 1A, the paging signal SPG of a message indicating "response to page key input" is supplied to the microcomputer 140. When this signal SPG is supplied, the forming circuit 161 is generated by the microcomputer 140. Is controlled to form a paging signal SPG of a telegram indicating "holding of outside line", and the paging signal SPG is transmitted to the master device 2 (step 433).

Then, in the base unit 2, the paging signal SPG of the electronic message indicating "holding of outside line" is sent to the microcomputer 24.
0 is supplied to the NCU 23 by the microcomputer 240.
0 is controlled and the line 3 is put on hold.

Subsequently, the master unit 2 forms a command signal CMND of a message indicating that "the outside line has been held", and this signal CMND is transmitted to the slave unit 1B (step 44).
1) When this signal CMND is received by the handset 1B,
In the handset unit 1B, a command signal CMND of a telegram indicating "a response to holding the outside line" is formed, and this signal CMND is transmitted to the base unit 2 (step 442). Then, when this signal CMND is received by the master unit 2, the master unit 2 forms a command signal CMND of a message indicating "confirmation", and this signal CMND is transmitted to the slave unit 1B (step 443).

Further, in the base unit 2, the microcomputer 24
The switch circuit 225 is switched by 0, the output signal of the reception circuit 221 is supplied to the transmission circuit 216 as an input signal, the output signal of the reception circuit 226 is supplied to the transmission circuit 215 as an input signal, and the output of the reception circuit 226 is output. The signal is supplied to the detection circuit 262.

Therefore, thereafter, when the user of the slave unit 1B speaks into the transmitter 111, the voice signal ST is transmitted to the master unit 2 by the FM signal SU of the upstream channel, and this FM signal SU is transmitted. , The voice signal ST of the user of the handset 1B is extracted by the receiving circuit 226, and this voice signal ST is supplied to the transmitting circuit 215 through the switch circuit 225 and the FM of the downlink channel is supplied.
The signal SD is transmitted to the handset 1A (step 45).
1). Therefore, from the receiving circuit 121 of the cordless handset 1A,
The voice signal ST of the user of the handset 1B is taken out, and this voice signal ST is supplied to the handset 124.

When the user of the slave unit 1A speaks into the transmitter 111, the voice signal ST thereof is transmitted to the master unit 2 by the FM signal SU of the upstream channel, and the FM signal SU is received. The voice signal ST of the user of the cordless handset 1A is extracted by the circuit 221 and the voice signal ST is transmitted through the switch circuit 225 to the transmitter circuit 2
It is supplied to 16 and is transmitted to the handset 1B by the FM signal SD of the downlink channel (step 451). Therefore, the voice signal ST of the user of the handset 1A is taken out from the receiving circuit 121 of the handset 1B, and the voice signal ST is supplied to the handset 124.

Therefore, an extension call can be made through the base unit 2 between the handset 1A and the handset 1B. At this time, between the handset 1A and the base unit 2, the channel that has been used for a call between the handset 1A and the outside line is used as it is without interruption. Further, another new channel will be used between the slave unit 1B and the master unit 2.

Then, when the extension call between the handset 1A and the handset 1B is completed, the page key of the handset 1B is pressed,
This is detected by the microcomputer 140, and the microcomputer 14
The forming circuit 161 is controlled by 0 to form a paging signal SPG of a telegram indicating "end of extension call", and the paging signal SPG is transmitted to the master unit 2 (step 461).

Then, in the base unit 2, the paging signal SPG of the electronic message indicating "end of extension call" is supplied to the microcomputer 240. Then, the forming circuit 261 is controlled and "response of end of extension call". Is generated, and the paging signal SPG is transmitted to the child device 1A (step 462).

The paging signal SPG is transmitted to the slave unit 1
When received at B and supplied to the microcomputer 140,
The forming circuit 161 is controlled to form the paging signal SPG of a message indicating "release of hold", and the paging signal SPG is transmitted to the master device 2 (step 463).

The paging signal SPG is transmitted to the base unit 2
When it is received by the microcomputer 240 and supplied to the microcomputer 240, the microcomputer 240 controls the NCU 230 to release the hold of the line 3, the line 3 is connected to the amplifiers 212 and 223 through the NCU 230, and the switch circuit 2
25 is controlled so that the adding circuit 214 is connected to the transmitting circuit 215, and the receiving circuit 221 is connected to the bandpass filter 222 and the detecting circuit 262. Therefore, thereafter, the user of the cordless handset 1A and the partner of the outside line can resume the call through the cordless handset 2 (step 471).

In this way, in the present case, even if any child device 1A is talking to the other party of the outside line through the parent device 2, if the page key of another child device 1B is pressed, the child device 1B will have the child device 1A.
Is notified that the extension call is requested, and if the handset 1A responds to the request, the extension is held and the extension call can be made between the handset 1B and the handset 1A. And
When the extension call is finished, the call between the handset 1A and the outside line can be resumed.

In the above description, the paging signal S
The frequency of the PG is set to be outside the band of the audio signals ST and SR,
The audio signals ST and SR are supplied to a narrow band band eliminate filter to remove a part of them so that the formants of the audio signals ST and SR are not significantly impaired, and the removed frequencies are the frequencies of the paging signal SPG. It can also be

[0061]

As described above, according to the present invention, even when the handset unit 1 is talking to the other party of the outside line through the base unit 2, if the page key of the base unit 2 is pressed, the base unit 2 is activated. If the handset 1 is notified that the extension call is requested and the handset 1 responds to this, the extension is held and the extension call can be made between the base 2 and the handset 1. it can. When the extension call is finished, the call between the handset 1 and the outside line can be resumed.

Moreover, the user of the base unit 2 cannot know the partner of the outside line with which the handset 1 is talking, and the privacy of the user of the handset 1 can be protected.

Alternatively, even when an arbitrary cordless handset 1A is talking to the other party of the outside line through the cordless handset 2, another cordless handset 1B is used.
When the page key is pressed, the handset 1B is notified that the handset 1A is requesting an extension call, and the handset 1A
If the answer is, the outside line is put on hold and an extension call can be made between the handset 1B and the handset 1A. Then, when the extension call is finished, the call between the handset 1A and the outside line can be resumed.

Also in this case, the user of the cordless handset 1B cannot know the outside line with whom the cordless handset 1A is talking, and the privacy of the user of the cordless handset 1A can be protected. ..

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a slave unit according to the present invention.

FIG. 2 is a system diagram showing an example of a master unit according to the present invention.

FIG. 3 is a sequence diagram when executing an extension call between a child device and a parent device.

FIG. 4 is a diagram showing a part of a sequence at the time of executing an extension call between two slave units.

FIG. 5 is a sequence diagram showing a continuation of FIG.

[Explanation of symbols]

 1, 1A to 1N Slave device 2 Master device 3 Telephone line 111, 211 Transmitter 115, 215, 216 Transmitter circuit 121, 221, 226 Receive circuit 124, 224 Receiver 140, 240 Microcomputer 161, 261 Paging signal forming circuit 162 , 262 Paging signal detection circuit

Claims (4)

[Claims] 1. A page key, a forming circuit for forming a control signal of a frequency outside a band of a voice signal when the page key is operated, and a transmission for transmitting the control signal together with a voice signal of a call to a partner device. A circuit and a detection circuit that detects the control signal when the control signal is transmitted from the partner device, and when the control signal is transmitted from the partner device,
A cordless telephone which, when the page key is operated, holds an outside line and switches to a connection for a call between the partner machine and the own machine. 2. The master unit and the slave unit each include a page key, a forming circuit that forms a control signal of a frequency outside a band of an audio signal when the page key is operated, and the control signal for calling. It has a transmission circuit that transmits to the other device together with a voice signal, and a detection circuit that detects the control signal when the other device transmits the control signal, and the slave device is connected to the outside line through the master device. When the page key of the master unit is operated, the control signal indicating that the page key is operated is transmitted from the master unit to the slave unit together with the audio signal from the outside line. In response to this transmission, when the page key is operated in the slave unit, the fact that the page key is operated is notified from the slave unit to the master unit by the control signal, and the master unit is operated. , Upon detection of the above-mentioned notification from the said child machine,
A cordless telephone that holds the outside line and makes a connection for a call between the master unit and the slave unit. 3. The master unit, the first slave unit, and the second slave unit each form a page key and a control signal having a frequency outside a band of an audio signal when the page key is operated. A circuit, a transmission circuit for transmitting the control signal together with a voice signal of a telephone call to a partner device, and a detection circuit for detecting the control signal when the partner device sends the control signal, When the slave unit of the second slave unit is connected to an external line through the master unit and the page key of the second slave unit is operated, the control signal indicating that the page key is operated is The second slave unit transmits to the first slave unit through the master unit, and in response to this transmission, when the page key is operated in the first slave unit, the page key is operated. However, according to the control signal, the first When the base unit notifies the base unit and the base unit detects the notification from the first base unit, the base unit holds the outside line, and the first base unit and the second base unit. A cordless phone that connects to and through the above main unit. 4. A cordless telephone slave unit comprising a page key, a forming circuit for forming a control signal of a frequency outside a band of a voice signal when the page key is operated, and the control signal for calling. It has a transmission circuit for transmitting to the master unit together with an audio signal and a detection circuit for detecting the control signal when the control signal is transmitted from the master unit, and the slave unit is connected to an external line through the master unit. When the control signal indicating that the page key of the master unit has been operated is transmitted together with the audio signal from the outside line, in response to this transmission, when the page key is operated, A control signal indicating that the page key has been operated is notified to the master unit, and the master unit holds the outside line and connects to the slave unit for a call. Dress phone.