JP2000138751A - Cordless telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop power supply to a radio control part in speech communication to reduce power consumption and to insure the reduction of a keypad from a master unit and speech communication for a long time at service interrupt, by feeding the power of auxiliary power supply to the radio control part of the master unit only, when call out is performed at service interruption, making a call out by utilizing the call out procedure of a slave unit and performing speech communication after connection by using a handset mounted on the master unit. SOLUTION: This telephone set comprises auxiliary power supply 12, a radio control part 14, a handset 16 and a cordless slave unit. Then, feeding to the radio control part 14 is started by an off-hook operation of the handset 16, while a master unit 10 operates by the auxiliary power supply 12 at service interrupt, and a call out is performed by using the keypad of a slave unit after radio connection with a slave unit. The connection with the slave unit is disconnected while the connection destination calls or communicates, and the feeding to the radio controlling part 14 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone, and more particularly, to an analog cordless telephone, a digital cordless telephone, or a wireless TA capable of registering a cordless handset, in which a base unit makes a call. The present invention relates to a cordless telephone characterized by the above configuration.

[0002]

2. Description of the Related Art In a cordless telephone, a digital cordless telephone, or a wireless TA in which a cordless cordless handset can be registered, normal operation is performed using electric power supplied from the outside. FIG. 5 is a block diagram showing a typical example of a conventional cordless telephone.
0 is a power supply switching circuit 41, an auxiliary power supply 42, a wireless control unit 4
4, master unit control unit 45, handset 46, ringer 47,
It comprises a keypad 48 and the like, and operates using electric power supplied from an auxiliary power supply built in or external to the parent machine at the time of power failure. Further, in a cordless telephone without an auxiliary power supply, a telephone call with the master unit is realized using a power supply supplied from a network limited to only a telephone call function.

In other words, the following two methods are conceivable as methods for guaranteeing a call during a power failure by a conventional method. (1) A telephone function is provided to the base unit, and a call is guaranteed using power supplied from the network. At this time, the base unit must be equipped with a handset and a keypad, and have a function that allows only the base unit to talk (the wireless part does not operate). (2) Using the auxiliary power supply and supplying power to the master unit in the event of a power outage guarantees a call by the slave unit (the wireless part also operates).

FIG. 6 shows the configuration of a master unit according to the conventional example shown in (1). The master unit according to this example has a handset and a keypad, but does not have an auxiliary power supply. Therefore, when the supply of external power is stopped during a power failure, the power supply switching circuit 41
The power supplied from the network is supplied to the parent device control unit 45 by the operation of, and at the same time, the power supply to the wireless control unit 44 is stopped. At this time, that is, in the event of a power outage, if a call is to be made using the power supplied from the network, the handset 46 is set to an off-hook state, and the connection destination number is input from the keypad 48;
Talk after answering the connection destination and handset 4 after ending the call
Generally, a procedure of on-hook 6 is performed.

FIG. 7 shows the structure of a master unit according to the prior art shown in (2). Since the master unit according to this example does not have a handset and a keypad, when the supply of external power is stopped during a power failure, the power supply switching circuit 41 operates to supply power from the auxiliary power source 42 to all parts of the master unit. Is supplied. In this case, even at the time of a power failure, a call is made using the slave unit and a call is made as in the normal case.

[0006]

As described above, as described above, in order to guarantee a call during a power outage in the method (1),
The handset and keypad must be provided on the master unit. However, in this system, a cordless telephone that uses a cordless handset for a normal call must have a handset and a keypad that are rarely used only for a power outage.

In the method (2), power must always be supplied to the wireless control unit even at the time of a power failure, and a large-capacity auxiliary power supply is provided to guarantee a sufficient talk time at the time of a power failure. And the cost and weight increase.

[0008]

The present invention comprises an auxiliary power supply,
It is composed of a base unit having a wireless control unit, an earphone (speaker) having a handset, or an earphone (speaker) as a substitute for the handset and a microphone, and a cordless handset. The power supply to the wireless control unit is started by connecting the earphone (speaker) and the microphone to the master unit, and after being wirelessly connected to the slave unit, a call is made using the keypad of the cordless slave unit.
When the connection destination is calling or talking, the connection with the slave unit is disconnected, and the power supply to the wireless control unit is stopped. The connection destination is a phone call using the handset of the master unit.

According to a first aspect of the present invention, there is provided an auxiliary power supply connected to a network and for guaranteeing operation at the time of a power failure, and a radio control which is normally supplied from an external power supply and supplied from the auxiliary power supply during a power failure. Unit, a base unit having a handset, and a cordless telephone including a cordless handset attached to the base unit, while operating with an auxiliary power supply, stopping power supply to the wireless control unit when in a standby state. When the off-hook state of the handset is detected, the power supply to the wireless control unit is started, the wireless control unit is operated, connection information is transmitted / received to / from the network according to the calling procedure of the cordless handset, and connection is performed by a signal from the network. When the other party is calling or talking, the connection to the cordless slave unit is cut off, the power supply to the wireless control unit is stopped, and the communication with the connection destination is performed using the handset of the master unit. Ko In a cordless telephone system that uses a handset during a normal call and does not use the handset and keypad of a base phone, it is possible to effectively use electric energy during a power outage and to guarantee operation during a power outage. It is not necessary to provide the keypad only in the master unit.

According to a second aspect of the present invention, there is provided an auxiliary power supply connected to a network for guaranteeing operation at the time of a power failure, and a radio control which is supplied with power from an external power supply at normal times and is supplied from the auxiliary power supply at a power failure. Unit, a headset having an earphone / microphone jack for inserting an earphone / microphone plug to which an earphone and a microphone are connected, and a cordless telephone configured from a cordless handset attached to the base, while operating with an auxiliary power supply, In the standby state, the power supply to the wireless control unit is stopped, and the power supply to the wireless control unit is started by the off-hook operation by inserting the earphone microphone plug into the earphone microphone jack of the master unit, and the wireless control unit is operated. When the connection information is transmitted and received to and from the network by the calling procedure of the cordless handset, and the connection destination is calling or busy with a signal from the network A cordless telephone, characterized in that the connection to the cordless handset is cut off, the power supply to the wireless control unit is stopped, and the call with the connection destination is made using an earphone and a microphone connected to the base unit. The electric energy inside can be used effectively, and it is not necessary to provide the master device with a keypad, and it is sufficient to connect an earphone / microphone set instead of the handset only at the time of power failure.

According to a third aspect of the present invention, a stop timer is used as means for determining the timing of stopping power supply to the wireless control unit, and when a signal indicating that a connection destination is being called or busy is received from a network. The cordless telephone according to claim 1 or 2, wherein the stop timer is started, and the power supply to the wireless control unit is stopped when the timer expires. Since this is performed when the stop timer expires, prompt recall can be performed before the timer expires.

According to a fourth aspect of the present invention, there is provided a cordless telephone using a speaker and a microphone instead of a handset as a means for talking to a connection destination. There is no need to connect the handset or an earphone (speaker) and a microphone in place of the handset to the master unit only during a power outage.

According to a fifth aspect of the present invention, there is provided a cordless telephone in which the base unit has an auxiliary power supply and performs a wireless connection with the cordless handset by an off-hook operation of the base unit in the event of a power failure, wherein the base unit has an earphone microphone jack. A cordless telephone having an off-hook operation to insert an earphone microphone plug in the event of a power outage, which does not require a permanent handset in the base unit, and uses the earphone microphone set used in a mobile phone or the like as the base unit. , You can talk.

According to a sixth aspect of the present invention, there is provided a cordless telephone in which the base unit has an auxiliary power supply and performs a wireless connection with the cordless handset by an off-hook operation of the base unit in the event of a power failure. This cordless telephone is characterized in that it does not perform the connection operation of the slave unit even if the base unit off-hook operation is performed during the detection of an incoming call at the time of a power failure. There is no need to connect a device and the sub device is not called, so that the auxiliary power is not consumed and the battery of the sub device is not consumed, so that the battery energy during the power failure is effectively used.

According to a seventh aspect of the present invention, there is provided a cordless telephone in which the base unit has an auxiliary power supply and performs a wireless connection with the cordless slave unit by off-hook operation of the master unit during a power failure, and dials from the slave unit after the wireless connection. A cordless telephone characterized by transmitting slave unit disconnection information at the slave unit and detecting the slave unit disconnection information at the master unit, the master unit stops supplying power to the wireless control unit, By transmitting the disconnection information from the slave unit to the master unit, the wireless controller power supply at the master unit can be stopped without unnecessary use of the slave unit after dialing.
The auxiliary power supply can be used effectively.

The invention according to claim 8 is a cordless telephone characterized in that the operation of transmitting the handset disconnection information is an operation of turning off the power of the handset. Since the operation is cut off by turning off the power, the battery of the slave unit can be used effectively, and the connection of the slave unit is cut off by the same operation as usual, so that the operation is unified without the user getting lost.

According to a ninth aspect of the present invention, the slave unit disconnection information detecting means is means for detecting that a radio wave from the slave unit received by the master unit is weaker than a threshold value. A cordless telephone having the same features as the eighth aspect of the present invention.

[0018] In a tenth aspect of the present invention, the cordless telephone is characterized in that the slave unit disconnection information is digital data received from the slave unit. If the specified dial data is specified, the specified dial data is transmitted from the slave unit, and then the disconnection data is sent immediately to enable the connection termination operation. The auxiliary power supply of the parent device and the battery of the child device can be used effectively.

The invention according to claim 11 is a cordless telephone having an auxiliary power supply in the master unit, performing a wireless connection with the cordless slave unit by off-hook operation of the master unit during a power failure, and dialing from the slave unit after the wireless connection. Therefore, when a plurality of slave units can be connected, a cordless telephone characterized by calling all or some of the slave units, without specifying a slave unit that is close to the user. Since a plurality of slave units are called, the user can use the called slave unit by connecting and operating a nearby slave unit, thereby improving the convenience.

[0020]

FIG. 1 is a block diagram of a first embodiment of the present invention. In FIG. 1, a base unit 10 includes a power supply switching unit 11, an auxiliary power supply 12, a wireless power control unit 13, a wireless control unit 14, a base unit control unit 15, a handset 16, and a ringer 1.
7. Consists of a hook switch 19. Note that a keypad or a dial is not required for the master unit, but may be provided. The power supply switching circuit 11 determines the presence or absence of an external power supply, and supplies power from the auxiliary power supply 12 to the master unit when power supply from the external power supply stops during a power failure. The auxiliary power supply 12 is composed of a primary battery, a secondary battery, or a large-capacity capacitor, and is a power supply that supplies power to the master unit when power from the outside is not supplied. The wireless power control unit 13 controls on / off of power supply to the wireless control unit according to an instruction from the base unit control unit 15, and the wireless control unit 14
This is a circuit that controls the radio unit of the master unit. Base unit control unit 15
Is a circuit other than the wireless part of the base unit, and I / F with the network,
Performs protocol processing and application processing.

Normally, when power is supplied from the outside, the power supply switching circuit 11 supplies the power supplied from the external power supply to the entire master unit. At this time, the wireless power control unit 13 operates to also supply power to the wireless control unit 14, but at the time of a power failure, the parent device enters a standby state in the following procedure.

When the power supply from the external power supply stops at the time of the power failure, the power supply switching circuit 11 supplies the power to the master unit to the auxiliary power supply 1.
Switch to supply from 2. Base unit control unit 15
When the power supply from the auxiliary power supply is detected, the wireless power control unit 13 is instructed to stop supplying power to the wireless control unit 14. Wireless power control section 13 stops power supply to wireless control section 14 according to an instruction from base unit control section 15. At the time of standby, in the base unit control unit 15, the I / F with the network and the protocol processing unit are operating.
By ringing 7, the incoming call is displayed, and the speaker talks via the handset 16.

Next, FIG. 2 shows a flow when a speaker makes a call. A calling procedure according to the present invention will be described with reference to FIGS. By bringing the handset 16 into the off-hook state (step S1), the base unit control unit 15 sends a dial tone to the handset (step S2). At the same time, base unit control unit 15 instructs wireless power control unit 13 to supply power to wireless control unit 14 (step S
3).

When power is supplied and the radio control unit 14 starts operating, a call can be made with the slave unit, and the speaker performs call processing using the slave unit in a normal calling procedure (step S).
4). Thereafter, when the parent device receives a signal indicating that the network is calling a connection destination (step S5), the parent device control unit 15 sends a ringing tone to the handset 16 (step S6), and at the same time, the wireless control unit 14 (Step S7).

When the communication with the slave unit is disconnected, the master unit control unit 15 instructs the wireless power control unit 13 to stop supplying power to the wireless control unit 14, and thereafter, the wireless power control unit 1
3 stops the power supply to the wireless control unit 14 (step S8). When the connection destination answers the telephone, a call can be made using the handset 16 (step S9). When the call ends, the speaker returns to the initial state by turning the handset on-hook (step S10).

In step S5, when the connection destination is busy, the base unit control unit 15 transmits a busy sound to the handset 16 (step S11) and disconnects the call with the slave unit. An instruction is issued to the wireless control unit 14 (step S12). Thereafter, the wireless power control unit 13 stops supplying power to the wireless control unit 14 (step S13), and the speaker sets the handset to the on-hook state,
The process returns to the initial state (Step S14).

As described above, the power supply to the radio control unit is limited only to the calling processing, and the power supply to the radio control unit during the call and the standby is stopped. Power consumption can be reduced.

In the above-described first embodiment, the power supply of the radio control unit 14 after the calling process is turned off after confirming that the calling or calling is in progress. In order to be able to make a call promptly, it is also possible to use a timer and cut off the power supply to the wireless control unit 14 after expiration.

FIG. 3 shows the flow at this time. By setting the handset 16 to the off-hook state (step S21), the base unit control unit 15 sends a dial tone to the handset (step S22). At the same time, base unit control unit 15 checks the state of wireless control unit 14 (step S23). If power is not supplied to the wireless control unit, power is supplied to wireless power control unit 13 to wireless control unit 14. It is instructed to supply (step S24).

When the radio control unit 14 starts operating, a call can be made with the slave unit, and the speaker performs a calling process using the slave unit in a normal calling procedure (step S25). After that, when the master unit receives a signal indicating that the network is calling the connection destination,
Master device controller 15 sends a ringing tone to handset 16 (step S27), and simultaneously instructs wireless controller 14 to disconnect the call with the slave device (step S28).

When the call with the slave unit is disconnected, the master unit control unit 15 starts a wireless control unit disconnection timer (step S2).
9). When the connection destination answers the telephone, a call can be made using the handset 16 (step S30). When the call ends, the speaker returns to the initial state by setting the handset to the on-hook state (step S31). When the wireless control unit disconnection timer expires during the call or after the call ends, the base unit control unit 15 instructs the wireless power supply control unit 13 to stop supplying power to the wireless control unit 14,
After that, the wireless power control unit 13 stops supplying power to the wireless control unit 14.

When the connection destination is busy, the master unit control unit 1
5 sends a busy tone to the handset 16 (step S32), and instructs the wireless control unit 14 to disconnect the call with the slave unit (step S33). When the call with the slave unit is disconnected, the base unit control unit 15 activates a wireless control unit disconnection timer (step S34), and the speaker returns to the initial state by setting the handset to the on-hook state (step S35). .

When the wireless control unit disconnection timer expires after the end of the call, the base unit control unit 15 instructs the wireless power control unit 13 to stop supplying power to the wireless control unit 14. Stops the power supply to the wireless control unit 14.

In the second embodiment, since the power supply to the radio control unit is stopped when the timer expires, it is possible to promptly make a call again before the timer expires.

FIG. 4 is a block diagram of a third embodiment of the present invention. The third embodiment is different from the first and second embodiments in that, besides the ringer 17 ringing at the time of an incoming call, an incoming call detecting unit 20 for detecting an incoming call from the network is provided. , Recognize that there is an incoming call. In the power failure state, the connection to the slave unit is not performed, and the user waits for the off-hook. When the user inserts the plug of the earphone microphone into the earphone microphone jack (with a plug insertion detection switch) 22 of the base unit, the switch for detecting this is turned ON, whereby the base unit control unit 15 recognizes that it is off-hook, and And connect the audio to the earphone microphone. At this time, an off-hook is detected, but since it is known from the incoming call detection that the operation is not a calling operation, dial operation is not required and connection to the slave unit is not performed. It goes without saying that a speaker or the like can be used instead of the earphone of the earphone microphone.

At the time of outgoing call during a power failure, the user sets the earphone microphone jack (with a plug insertion detection switch)
By inserting the plug of the earphone microphone, a switch for detecting this is turned ON, whereby the base unit control unit 15 recognizes that the hook is off-hook and captures the line. On the other hand, power is supplied from the auxiliary power source to the wireless unit, and the slave units are simultaneously called to set an incoming call state, and only the slave unit to which the user has performed a response operation is connected. This is for dialing from the slave unit. The user dials from the handset. At this time, the telephone directory data can be specified. The master unit receives the dial data from the slave unit and sends a predetermined (pulse or tone) dial to the line. After dialing, the user presses the on-hook button to disconnect the slave unit. The master unit receives the data for disconnecting from the slave unit, and disconnects the connection with the slave unit. At this time, the sound of the line and the sound of the earphone microphone are mutually connected. For calling.

Regardless of whether the call is made or not, the user who has finished the call removes the earphone microphone plug from the earphone microphone jack, so that the switch is turned off, and the master unit hooks up the line to disconnect.

In the above description, the on-hook button is pressed on the slave unit to indicate that the dialing has been completed on the slave unit, and this operation is transmitted to the master unit by data to disconnect the connection with the slave unit. The operation of turning off the power is performed by the radio wave intensity detection unit 21 that detects the intensity of the radio wave from the slave unit at the master unit.
Is provided and the radio wave from the slave unit is detected, so that the master unit can determine that dialing in the slave unit has been completed.

When the telephone directory data is designated, when the data in the telephone directory is transmitted to the master unit, the dial data can be transmitted.
The slave unit may immediately perform the on-hook processing.

[0040]

According to the present invention, the following effects can be expected in the operation during a power failure. (1) In a cordless telephone system that uses a slave unit during a normal call and does not use a master unit, there is no need to provide a keypad in the master unit only to guarantee operation during a power failure.

(2) Since power is supplied to the radio control unit only at the time of calling, power consumption can be reduced at the time of power failure, and long-term operation using the auxiliary power supply can be guaranteed.

(3) The keypad of the slave unit is used for inputting the telephone number of the other party. However, since the calling procedure is the same as the calling procedure from a normal slave unit, a special slave unit is required. Not
Any child device that can be registered in the parent device can be used.

(4) According to the first aspect of the present invention, in a cordless telephone system that uses a slave unit during a normal call and does not use a handset and a keypad of the master unit, battery energy during a power outage can be effectively used. Also, it is not necessary to provide a keypad in the master unit only to guarantee operation at the time of power failure.

(5) According to the second aspect of the invention, the battery energy during the power failure can be used effectively, and it is not necessary to provide the master unit with a keypad, and the earphone / microphone set instead of the handset is powered down. You only need to connect when you are.

(6) According to the third aspect of the present invention, the power supply to the radio control unit is stopped by the expiration of the stop timer.

(7) According to the invention of claim 4, it is not necessary to always have a handset in the base unit, and it is possible to communicate by inserting an earphone microphone set used in a mobile phone or the like into the base unit. Since the handset only needs to be connected to the master unit during a power outage, the installation area of the master unit does not increase.

(8) According to the fifth aspect of the present invention, it is not necessary to always have a handset in the base unit, and a telephone call can be made by inserting an earphone microphone set used in a mobile phone or the like into the base unit.

(9) According to the sixth aspect of the present invention, when an incoming call is received, no dial operation is required, so that there is no need to connect a slave unit, and since the slave unit is not called, the auxiliary power is not consumed. Also, the battery of the slave unit is not consumed, so that the battery energy during the power failure can be used effectively.

(10) According to the seventh, eighth, and ninth aspects of the present invention, the disconnection information is transmitted from the slave unit to the master unit, so that useless connection with the slave unit after dialing is completed can be performed. Since the power supply to the wireless unit can be stopped, the auxiliary power can be used effectively. Also, disconnect the slave unit using the same operation as usual,
There is an advantage that the user can perform the operation without hesitation and the operability is unified.

(11) According to the eighth and ninth aspects of the present invention, since the connection is cut off by turning off the power of the slave unit, the battery of the slave unit can be used effectively, and the dial operation can be performed even for the master unit. Termination can be detected.

(12) According to the tenth aspect, when dial data stored in the telephone directory is designated by the slave unit, the designated dial data is transmitted from the slave unit and immediately thereafter. By transmitting the disconnection data to the terminal, the connection termination operation can be enabled, and the auxiliary power supply of the master unit and the battery of the slave unit used for the radio wave connection can be used effectively.

(13) According to the eleventh aspect of the present invention, since a plurality of sub units are called without specifying a sub unit near the user, the user is closer to the called sub units. It can be used by connecting and operating a slave unit, and convenience is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a base unit of a cordless telephone according to the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment of the cordless telephone of the present invention.

FIG. 3 is a flowchart showing the operation of the second embodiment of the cordless telephone of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the base unit of the cordless telephone according to the present invention.

FIG. 5 is a block diagram of a base unit of a conventional cordless telephone.

FIG. 6 is a block diagram of a parent device of a conventional cordless telephone.

FIG. 7 is a block diagram of a parent device of a conventional cordless telephone.

[Explanation of symbols]

10: master unit, 11: power supply switching circuit, 12: auxiliary power supply, 1
3: Wireless power control unit, 14: Wireless control unit, 15: Master unit control unit, 16: Handset, 17: Ringer, 19: Hook switch, 20: Incoming detection unit, 21: Radio field intensity detection unit, 22: Earphone microphone Jack (with plug insertion detection switch).

Claims (11)

[Claims] An auxiliary power supply connected to a network and guaranteeing operation at the time of a power failure, a radio control unit normally supplied with power from an external power supply at the time of power failure and supplied with power from the auxiliary power supply, and a handset. In a cordless telephone comprising a base unit having the base unit and a cordless handset attached to the base unit, during operation with an auxiliary power supply, when in a standby state, power supply to the wireless control unit is stopped, and an off-hook state of the handset is set. To start the power supply to the wireless control unit by operating the wireless control unit, send and receive connection information to and from the network by the calling procedure of the cordless handset, and the connection destination is calling or A cordless telephone characterized by disconnecting a cordless handset and stopping power supply to a wireless control unit during a call, and making a call to a connection destination using a handset of the base unit. 2. An auxiliary power supply connected to a network and guaranteeing operation at the time of power failure, a radio control unit which is normally supplied with power from an external power supply at the time of power failure and is supplied with power from the auxiliary power supply, and an earphone and In a cordless telephone comprising an earphone microphone jack for inserting an earphone microphone plug connected to a microphone and a cordless handset attached to the parent device, when operating with an auxiliary power supply and in a standby state The power supply to the wireless control unit is stopped, the power supply to the wireless control unit is started by the off-hook operation by inserting the earphone microphone plug into the earphone microphone jack of the base unit, the wireless control unit is operated, and the cordless slave unit is operated. Sends and receives connection information to and from the network according to the calling procedure. When the connection destination is ringing or busy with a signal from the network, the cordless child Cordless telephone, characterized in that by cutting the connection with the stops power supply to the radio control unit, the call with the connected is performed at the earphone and microphone connected to the master unit. 3. A stop timer is used as means for deciding when to stop supplying power to the wireless control unit, and the stop timer is set when a signal indicating that a connection destination is being called or busy is received from a network. 3. The cordless telephone according to claim 1, wherein the cordless telephone is activated and stops supplying power to the wireless control unit when the timer expires. 4. The cordless telephone according to claim 1, wherein a speaker and a microphone are used instead of the handset as a means for communicating with the connection destination. 5. A cordless telephone which has an auxiliary power supply and performs a wireless connection with a cordless child device by an off-hook operation of the parent device during a power failure, wherein the parent device has an earphone microphone jack, A cordless telephone characterized in that inserting an earphone microphone plug is an off-hook operation. 6. A cordless telephone which has an auxiliary power supply and performs a wireless connection with a cordless slave unit by an off-hook operation of the master unit in the event of a power outage. A cordless telephone characterized in that a connection operation of a slave unit is not performed even if a base unit off-hook operation is performed during an incoming call detection. 7. A cordless telephone which has an auxiliary power supply and performs a wireless connection with a cordless slave unit by an off-hook operation of the master unit in the event of a power failure. A cordless telephone, wherein when the base unit transmits the handset disconnection information and the base unit detects the handset disconnection information, the base unit stops supplying power to the wireless control unit. 8. The cordless telephone according to claim 7, wherein the handset disconnection information transmitting operation is an operation of turning off the power of the handset. 9. The apparatus according to claim 7, wherein the detecting means of the handset disconnection information is means for detecting that a radio wave received from the handset from the handset has become weaker than a threshold value. Cordless telephone. 10. The cordless telephone according to claim 7, wherein the handset disconnection information is digital data received from the handset. 11. A cordless telephone having an auxiliary power supply in a master unit, performing wireless connection with a cordless slave unit by off-hook operation of the master unit during a power failure, and dialing from the slave unit after the wireless connection. A cordless telephone characterized by calling all or some of the slave units when the slave unit is connectable.