Cordless telephone system and its independent base station and mobile station

A cordless telephone system including a independent base station and a dual purpose mobile station which enables the mobile station to respond to an incoming call from a public base station while a first phone call is being conducted by the mobile station through the independent base station. During this operation, the first phone call is either put on hold or disconnected thus enabling the mobile station to shift to the call from the public base station. The independent base station is provided with a public reception antenna, a reception radio circuit, a mobile station reception channel CODEC, a public reception control section, and a public reception interface, enabling it to receive a call signal from the public base station intended for the dual purpose mobile station. Due to this constitution, the independent base station receives the call signal from the public base station intended for the dual purpose mobile station during the first phone call.

BACKGROUND OF THE INVENTION 
The present invention relates to a cordless telephone system and its 
independent base station and mobile station. More to particularly the 
present invention relates to a cordless telephone system and its 
independent base station and mobile station in which the mobile station is 
connected to a mobile communication network or a fixed network, and it is 
capable of executing radio communication both to outdoor public base 
station (hereinafter referring to public base station) in which original 
communication service control is executed, and to cordless telephone 
system independent base station (herein after referring to home 
independent base station) connected to the fixed network. 
DESCRIPTION OF THE PRIOR ART 
Formerly, a public base station and a home independent base station, and 
cordless telephone system mobile station (hereinafter referring to dual 
purpose mobile station) which is capable of executing time-division 
multiplex radio communication enable a telephone call executed through the 
public base station (hereinafter referring to outdoor public telephone 
call), and a telephone call executed through a home independent base 
station (hereinafter referring to indoor self-supporting call) to be 
performed. 
Hereinafter, the conventional cordless telephone system is described 
referring to the drawings. 
FIG. 1 is a block diagram showing a configuration of the home independent 
base station of the conventional cordless telephone system. The device of 
the independent base station comprises an antenna 104 for performing 
transmission-reception of radio wave, a transmitter-receiver radio circuit 
103 for executing demodulation of received radio waves and modulation of 
transmission data, an independent base station channel CODEC section 102 
for executing both decoding of demodulation signals from the 
transmitter-receiver radio circuit 103 and coding of transmission data, a 
call/circuit control section 101 for executing voice coding of received 
sound signals from the fixed network and voice decoding of voice data 
decoded at the independent base station channel CODEC section 102 and for 
receiving a call signal from the fixed network, a home independent base 
station control section 505 for executing power control among the 
call/circuit control section 101, the independent base station channel 
CODEC section 102, and transmitter-receiver radio circuit 103, and for 
executing communication protocol control between the independent base 
station and mobile station. 
FIG. 2 is a block diagram showing a configuration of a dual purpose mobile 
station of the conventional cordless telephone system. The conventional 
dual purpose mobile station comprises an antenna 204 for 
transmission-reception of radio waves, a transmitter-receiver radio 
circuit 203 for executing demodulation of received radio waves and 
modulation of transmission data, a dual purpose mobile station channel 
CODEC section 202 for executing decoding of demodulation signals from the 
transmitter-receiver radio circuit 203 and coding of transmission data, a 
speaker 206 for outputting voice audio, a microphone 207 for inputting 
voice audio, a telephone call control section 201 for executing voice 
coding of received sound signals from the microphone 207 and voice 
decoding of voice data decoded at the dual purpose mobile station channel 
CODEC section 202, and a dual purpose mobile station control section 605 
for executing power control among the telephone call control section 201, 
the dual purpose mobile station channel CODEC section 202, and the 
transmitter-receiver radio circuit 203, and for executing communication 
protocol control between the home independent base station and the dual 
purpose mobile station control section or between the public base station 
and the same. 
FIG. 3 is a view showing an operational environment of the conventional 
cordless telephone system. In this conventional cordless telephone system, 
a dual purpose mobile station 802 is capable of executing the telephone 
call through the home independent base station 801, and is capable of 
receiving radio waves from the public base station 403. However, when the 
dual purpose mobile station 802 is conducting a telephone call through the 
home independent base station, it is impossible to respond to an incoming 
call because the dual purpose mobile station 802 is incapable of receiving 
the radio waves from the public base station 403 so that it is incapable 
of receiving a call signal (822). The dual purpose mobile station 802 
receives the call signal 822 which both the public base station 403 and 
the home independent base station 801 transmit intermittently while 
waiting the incoming from both of the public base station 403 and the home 
independent base station 801. 
Subsequently, as shown in FIG. 4, when the timing of reception processing 
overlaps, the reception processing of the call signal (805) from the 
public station 403 is preferred, so that the dual purpose mobile station 
802 does not perform the reception processing of the call signal (805) 
from the home independent base station 801. For this reason, the home 
independent base station 801 assumes that the dual purpose mobile station 
802 is not within the reception area capable of receiving radio waves 
because it has not received a response from the dual purpose mobile 
station 802 in relation to the call signal 804. Further, in the reception 
processing, it is also possible to establish a preference for the home 
independent base station. In the dual purpose mobile station, when the 
call signal (805) is received from the public base station 403, the 
incoming processing steps 806 are executed between the dual purpose mobile 
station 802 and the public base station 403. At the end of the incoming 
processing 806, the dual purpose mobile station 802 transmits an 
in-calling signal (807) notifying the public base station 403 that the 
dual purpose mobile station 802 has recognized the incoming call. 
Simultaneously, the mobile station 802 transmits a ringing tone (808) for 
notifying the user of the incoming call. Subsequently, when the mobile 
station 802 detects a response (on hook (809)) from the user, the mobile 
station 802 shifts to the telephone call (811) and transmits response 
signal (810) to the public base station 403. When the telephone call is 
terminated, the mobile station returns to the incoming waiting state, and 
executes its disconnection processing (812). 
FIG. 5 is a view showing operation of the conventional call waiting 
notification (catch-phone). The call waiting notification is adapted in 
both of the fixed network and the mobile communication network as shown in 
the Japanese Patent Application Laid-Open No. HEI 06-85916 and the 
Japanese Patent Application Laid-Open No. HEI 6-6854. A separate incoming 
arrives at the home independent base station 801 when the dual purpose 
mobile station is on a first telephone call (813) through the home 
independent base station 801. The home independent base station 801 causes 
the call waiting notification 814 to be transmitted to the dual purpose 
mobile station 802, while simultaneously originating a ringing tone for 
notifying the user of the new incoming call. Subsequently, when there is 
hook manipulation (815) by the user, the dual purpose mobile station 802 
transmits the hooking signal (816) to the home independent base station 
801. In response, the network switches to the second telephone call, and 
thus, the second telephone call 817 becomes possible. When the second 
telephone call 817 is terminated and the user implements the hook 
manipulation 818 again, the dual purpose mobile station 802 transmits the 
hooking signal (819), thus returning to the first telephone call (820) due 
to the switching of the network. 
However, as shown in FIG. 6, although a call signal 822 is transmitted from 
the public base station 403 to the dual purpose mobile station while the 
dual purpose mobile station 802 is on an indoor self-supporting telephone 
call (821), the dual purpose mobile station 802 is incapable of responding 
to the incoming call 822 from the public base station 403 with the result 
that the dual purpose mobile station 802 continues the indoor 
self-supporting telephone call (823). 
This is the reason why, as shown in FIG. 1, the home independent base 
station of the conventional cordless telephone system includes the antenna 
104 for performing transmission-reception of radio waves the 
transmitter-receiver radio circuit 103 for executing both demodulation of 
received radio waves and modulation of transmission data, the independent 
base station channel CODEC section 102 for executing both decoding of the 
demodulation signals from the transmitter-receiver radio circuit 103 and 
coding of transmission data, the call/circuit control section 101 for 
executing voice coding of sound signals received from the fixed network 
and voice decoding of the voice data decoded at the independent base 
station channel CODEC section 102, and for receiving the call signal from 
the fixed network, and the home independent base station control section 
505 for executing power control of the call/circuit control section 101, 
the independent base station channel CODEC section 102, and the 
transmitter-receiver radio circuit 103, and for executing the 
communication protocol control in between the mobile station and the 
independent base station. The home independent base station 801 does not 
possess means for receiving the call signal transmitted from the public 
base station 403 to the dual purpose mobile station 802. As shown in FIG. 
2, the dual purpose mobile station of the conventional cordless telephone 
system includes the antenna 204 for performing transmission-reception of 
radio waves, the transmitter-receiver radio circuit 203 for executing both 
demodulation of received radio waves and modulation of transmission data, 
the dual purpose mobile station channel CODEC section 202 for executing 
both decoding of the demodulation signals from the transmitter-receiver 
radio circuit 203 and coding of the transmission data, the speaker 206 for 
outputting voice audio, the microphone 207 for inputting voice audio, the 
telephone call control section 201 for executing both voice coding of 
sound signals received from the microphone 207 and voice decoding of the 
sound data decoded at the dual purpose mobile station channel CODEC 
section 202, and the dual purpose mobile station control section 605 for 
executing power control of the telephone call control section 201, the 
dual purpose mobile station channel CODEC section 202, and the 
transmitter-receiver radio circuit 203, and for executing the 
communication protocol control in between the dual purpose mobile station 
and the home independent base station or the public base station. The dual 
purpose mobile station 802 does not possess the means for receiving the 
call signal transmitted asynchronously with the sound signal during a 
telephone call through the home independent base station. In conclusion, 
although the call signal is transmitted (822) from the public base station 
403 to the dual purpose mobile station 802 while the dual purpose mobile 
station is on the indoor self-supporting telephone call (821), the dual 
purpose mobile station is incapable of responding to the incoming call 
signal 822. 
Similarly, as shown in FIG. 7, although the call signal is transmitted 
(825) from the home independent base station 801 to the dual purpose 
mobile station 802 while the dual purpose mobile station 802 is on an 
outdoor public telephone call, the dual purpose mobile station 802 is 
incapable of responding to the incoming call signal 825, with the result 
that the dual purpose mobile station 802 continues the indoor 
self-supporting telephone call (826). The reason for this lack of 
capability is similar to the above described case of indoor 
self-supporting telephone call. The dual purpose mobile station 802 does 
not possess the means for receiving radio waves which are transmitted 
separately during the telephone call through the public base station 403, 
and the public base station 403 is incapable of receiving the call signal 
transmitted from the home independent base station 801 to the dual purpose 
mobile station 802 because the public base station 403 is incapable of 
finding the frequency of the radio waves by which the home independent 
base station 801 transmits the call signal, or the number of the dual 
purpose mobile station 802 in the cordless telephone system. 
FIG. 8 is a flow chart showing the operation of the dual purpose mobile 
station control section 605 while the dual purpose mobile station 802 is 
on the indoor self-supporting telephone call. After entering the indoor 
self-supporting telephone call state (701), when the dual purpose mobile 
station 802 detects on-hook (702), it proceeds to telephone call end state 
(715) after executing the telephone call disconnection processing (703) 
which is actuated from the mobile station 802. When the dual purpose 
mobile station control section 605 does not detect the on-hook (702), but 
receives the disconnection signal from the side of the home independent 
base station (704), it proceeds to the telephone call end state (715) 
after executing the telephone call disconnection processing (705) which is 
actuated from the side of the independent base station 801. If the dual 
purpose mobile station control section 605 does not receive the 
disconnection signal from the home independent base station (704), but 
detects the hold manipulation by the user (706), and if the indoor 
self-supporting telephone call is already in the hold state (707), 
transmission of voice communication is started (709) after executing 
processing for removing the hold state of the indoor self-supporting 
telephone call (708). If the user does not hold the indoor self-supporting 
telephone call (707), processing is executed to hold the indoor 
self-supporting telephone call (710). The dual purpose mobile station 802 
prevents transmission of audio (711), and plays a hold-melody (712) for 
notifying the hold to the user. When the dual purpose mobile station 802 
does not detect the hold-manipulation by the user (706), but detects the 
hook manipulation by the user (713), it executes the transmission 
processing requirement of the hooking signal 714 to the home independent 
base station 801. When the hook manipulation by the user is not detected 
(713), the dual purpose mobile station 802 maintains the indoor 
self-supporting telephone call. 
FIG. 9 is a flow chart showing operation of the home independent base 
station control section 505 while the dual purpose mobile station is on 
the indoor self supporting telephone call. After entering the indoor 
self-supporting telephone call state (716), when the home independent base 
station control section 505 receives the disconnection signal 717 from the 
dual purpose mobile station 802, it proceeds to the telephone call end 
state (730) after executing the telephone call disconnection processing 
718 which is actuated from the side of the mobile station 802. If the home 
independent base station 801 does not receive the disconnection signal 
from the dual purpose mobile station (717), but detects circuit 
disconnection (719), it proceeds to the telephone call end state (730) 
after executing the telephone call disconnection processing (720) which is 
actuated from the side of the independent base station 801. When the home 
independent base station 801 does not detect the circuit disconnection 
(719), but receives 721 the telephone call holding requirement from the 
dual purpose mobile station 802, it executes hold set processing (722) to 
prevent voice transmission (723), and plays the hold-melody (724) for 
notifying the hold state to the user. When the home independent base 
station 801 does not receive 721 the telephone call holding requirement 
from the dual purpose mobile station 802, but receives the hold removal 
requirement (725), it restarts the transmission of voice (727) after 
executing the hold removal processing (726). When the home independent 
base station control section 505 does not receive 725 the hold removal 
requirement from the dual purpose mobile station 802, but receives the 
hooking signal transmission requirement (728), it transmits the hooking 
signal to the fixed network (729). While when the home independent base 
station 801 does not receive the hooking signal transmission requirement 
(728), it maintains the indoor self-supporting telephone call. 
The problem points of the above-described conventional example are that 
although the public base station 403 transmits the call signal to the dual 
purpose mobile station 802, if the dual purpose mobile station is already 
on a telephone call with the home independent base station, the dual 
purpose mobile station 802 is incapable of responding to the incoming call 
from the public base station 403. Consequently, the dual purpose mobile 
station 403 is incapable of responding to the outdoor public telephone 
call during indoor self-supporting telephone call. Because the 
configuration of the dual purpose mobile station 802 does not enable it to 
receive the call signal transmitted with the different frequency from the 
signal of the indoor self-supporting telephone call and with the different 
timing therefrom. 
SUMMARY OF THE INVENTION 
In view of the foregoing, it is an object of the present invention to 
provide a cordless telephone system and its independent base station and 
mobile station which enables a home independent base station to receive a 
call signal transmitted from a public base station to a dual purpose 
mobile station instead of the dual purpose mobile station while the dual 
purpose mobile station is already in communication with the home 
independent base station. The dual purpose mobile station is capable of 
receiving both radio waves of the public base station and the home 
independent base station. After detection of the call from the public base 
station, the home independent base station transmits a call waiting 
notification signal to the mobile station which denotes that an 
accompanying control channel which is capable of performing 
transmission-reception of a control signal during the telephone call. The 
dual purpose mobile station enables the incoming call from the public base 
station to be implemented by receiving the call waiting notification 
signal. Thus the user of the mobile station is notified of the incoming 
call from the public base station which occurs during an indoor 
self-supporting telephone call, with the result that the cordless 
telephone system is capable of responding thereto. 
The present invention provides a cordless telephone system including an 
independent base station and mobile station in which the mobile station is 
connected to mobile communication network or fixed network. 
In one embodiment to be described below by way of example in illustration 
of the invention, a cordless telephone system includes an independent base 
station which is connected to a fixed network, a mobile station which is 
connected to the independent base station and either to a mobile 
communication network or a fixed network, and a public base station in 
which an original communication service control of the mobile 
communication is implemented. When the mobile station is communicating 
through the independent base station, the public base station attempts to 
transmit a call signal directly to the mobile station, but the independent 
base station receives the call signal instead of the mobile station. The 
independent base station transmits a call waiting notification signal to 
the mobile station which represents reception of the call signal during 
the telephone call between the mobile station and the independent base 
station. The mobile station receives the call waiting notification signal 
from the independent base station, and before executing the incoming 
processing between the mobile station and the public base station, it 
executes the hold operation of the present telephone call temporarily. 
When the incoming processing ends, calling the user by returning to the 
telephone call, and when there is a response from the user, enabling the 
mobile station itself to execute the telephone call to the public base 
station while either disconnecting or holding the telephone call toward 
the independent base station. When the telephone call toward the public 
base station is terminated, if the telephone call with the independent 
base station has been maintained in the hold state, the original telephone 
call is continued by removing the hold state. 
In one particular embodiment, there is an independent base station which 
includes an antenna for performing transmission-reception of radio waves, 
a transmitter-receiver radio circuit for executing both demodulation of 
received radio waves and modulation of transmission data, an independent 
base station channel CODEC section for executing both decoding of 
demodulation signals from the transmitter-receiver radio circuit and 
coding of transmission data, a call/circuit control section for executing 
both voice coding of a sound signal received from a fixed network, and 
voice decoding of voice data which is decoded at the independent base 
station channel CODEC section, and for receiving a call signal from the 
fixed network, a home independent base station control section for 
executing communication protocol control among the call/circuit control 
section, the independent base station channel CODEC section, a power 
source control for the transmitter-receiver radio circuit and a mobile 
station, a public reception antenna for receiving radio waves which are 
transmitted from a public base station, a reception radio circuit for 
executing demodulation of received radio waves from the public reception 
antenna, a mobile station reception channel CODEC section for executing 
decoding of demodulation signals from the reception radio circuit, a 
public reception control section for detecting a call signal for the 
mobile station from decoded data from the mobile station reception channel 
CODEC section to notify to the home independent base station control 
section, and a public reception interface section which is provided within 
the home independent base station control section for receiving call 
signal detection notification from the public reception control section. 
The independent base station receives a call signal which is transmitted 
from the public base station to the mobile station during the telephone 
call through the independent base station. Subsequently, the mobile 
station receives call waiting notification signal from the independent 
base station. Before the mobile station disconnects the telephone call 
through the independent base station by manipulation of the user, it is 
capable of shifting to the telephone call through the public base station. 
In another embodiment of the present invention, there is the independent 
base station which receives the call signal which is transmitted from the 
public base station to the mobile station during the telephone call state 
with the independent base station. Subsequently, the mobile station 
receives the call waiting notification signal from the independent base 
station. Before the mobile station shifts to the telephone call through 
the public base station, it places the original telephone call temporarily 
on hold through the independent base station by manipulation of the user. 
The on-hold state is removed after disconnection of the telephone call 
through the public base station, with the result that it is capable of 
being returned to the telephone call through the independent base station. 
In another embodiment of the present invention, there is a mobile station 
which includes an antenna for performing transmission-reception of radio 
waves, a transmitter-receiver radio circuit for executing both of 
demodulation of received radio waves and modulation of transmission data, 
a mobile station channel CODEC section for executing both decoding of 
demodulation signal from the transmitter-receiver radio circuit and coding 
of the transmission data, a speaker for outputting voice audio, a 
microphone for inputting voice, a telephone call control section for 
executing both voice coding of sound signals received from the microphone 
and voice decoding of voice data decoded at the mobile station channel 
CODEC section, a mobile station control section for executing both power 
control of the telephone call control section, the mobile station channel 
CODEC section, and the transmitter-receiver radio circuit and 
communication protocol control, and a call waiting notification detecting 
section which is provided in the mobile station control section, being 
capable of receiving the call waiting notification signal which represents 
that the public base station has transmitted a call signal to the mobile 
station through the independent base station while the mobile station 
control section is communicating through the independent base station. 
In further embodiment of the present invention, there is an independent 
base station which includes an antenna for performing 
transmission-reception of radio waves, a transmitter-receiver radio 
circuit for executing both demodulation of received radio waves and 
modulation of transmission data, a independent base station channel CODEC 
section for executing both decoding of demodulation signal from the 
transmitter-receiver radio circuit and coding of the transmission data, a 
call/circuit control section for executing voice coding of sound signals 
received from a fixed network, and voice decoding of voice data which is 
decoded at the independent base station channel CODEC section, and for 
receiving a call signal from the fixed network, a home independent base 
station control section for executing communication protocol control among 
the call/circuit control section, the independent base station channel 
CODEC section, a power source control of the transmitter-receiver radio 
circuit and a mobile station, a public reception antenna for receiving 
radio waves which are transmitted from a public base station, a reception 
radio circuit for executing demodulation of received radio waves from the 
public reception antenna, a mobile station reception channel CODEC section 
for executing decoding of demodulation signal from the reception radio 
circuit, and a public reception control section for detecting a call 
signal for the mobile station among the decoded data from the mobile 
station reception channel CODEC section to notify to the home independent 
base station control section, wherein when the public reception interface 
section receives a call signal detection notification from the public 
reception control section, the public base station transmits the call 
waiting notification signal notifying that it has caused the call signal 
to be transmitted to the mobile station. 
In yet another embodiment of the present invention, in an independent base 
station the home independent base station control section, the public 
reception interface section, and the public reception control section 
constitute one block or a plurality of blocks. 
In yet another embodiment of the present invention, in an independent base 
station, the independent base station channel CODEC section and the mobile 
station reception channel CODEC section constitute one block or a 
plurality of blocks. 
In yet a further embodiment of the present invention, in an independent 
base station, the transmitter-receiver radio circuit and the reception 
radio circuit constitute one functional block or a plurality of functional 
blocks. 
As explained above, the home independent base station of the cordless 
telephone system according to the present invention receives the call 
signal from the public base station during an indoor self-supporting 
telephone call in order to transmit the call waiting notification signal 
denoting that the accompanying control channel causes the call signal to 
be received. Subsequently, the dual purpose mobile station enables 
recognition of the incoming call from the public base station to be 
performed by virtue of the fact that the dual purpose mobile station 
receives the call waiting notification signal. More concretely, the dual 
purpose mobile station of the present invention comprises the antenna for 
performing transmission-reception of the radio waves, the 
transmitter-receiver radio circuit for executing both demodulation of 
received radio waves and modulation of transmission data, the dual purpose 
mobile station channel CODEC section for executing both decoding of 
demodulation signals from the transmitter-receiver radio circuit and 
coding of the transmission data, the speaker for outputting voice audio, 
the microphone for inputting voice audio, the telephone call control 
section for executing voice coding of sound signals received from the 
microphone and voice decoding of the voice data decoded at the dual 
purpose mobile station channel CODEC section, and the dual purpose mobile 
station control section for executing both power control and communication 
protocol control of the telephone call control section, the dual purpose 
mobile station channel CODEC section, and the transmitter-receiver radio 
circuit. In addition, there is provided the call waiting notification 
detection section which is capable of detecting the call waiting 
notification signal transmitted in such a way that the home independent 
base station transmits the notification by using accompanying control 
channel during indoor self-supporting telephone call. 
Further, the home independent base station of the present invention 
comprises the antenna for performing transmission-reception of the radio 
waves, the transmitter-receiver radio circuit for executing demodulation 
of received radio waves and modulation of transmission data, the 
independent base station channel CODEC section for executing both decoding 
of demodulation signals from the transmitter-receiver radio circuit and 
coding of the transmission data, the call/circuit control section for 
executing both voice coding of sound signal received from the fixed 
network and voice decoding of the voice data decoded at the independent 
base station channel CODEC section, and for receiving the call signal 
transmitted from the fixed network, the home independent base station for 
executing both the power control among the call/circuit control section, 
the independent base station channel CODEC section, and the 
transmitter-receiver radio circuit and the communication protocol control 
between the mobile station and the independent base station. In addition, 
there is provided the public reception interface section for notifying 
detection of reception of the call signal transmitted from the public base 
station to the dual purpose mobile station by using the accompanying 
control channel toward the dual purpose mobile station, the public 
reception antenna for receiving radio waves which is transmitted from the 
public base station, the reception radio circuit for executing 
demodulation of received radio waves from the public reception antenna, 
the mobile station reception channel CODEC section for executing decoding 
of the demodulation signal from the reception radio circuit, and the 
public reception control section which detects the call signal for the 
dual purpose mobile station among the decoding data from the mobile 
station reception channel CODEC section to notify it to the public 
reception interface section. Consequently, the home independent base 
station receives the call signal transmitted from the public base station 
to the dual purpose mobile station during indoor self-supporting telephone 
call. The accompanying control channel enables the incoming call to be 
notified to the dual purpose mobile station, thus the dual purpose mobile 
station is capable of responding to the incoming call. 
The home independent base station receives the radio waves from the public 
base station by the public reception antenna in order to receive the 
control signal from the public base station during the indoor 
self-supporting telephone call. The reception radio circuit demodulates 
the control signal which is then decoded at the channel CODEC section. The 
public reception control section in the home independent base station 
receives the call signal intermittently while deciding the reception 
timing of the control signal from the content of the decoded reception 
data. The public reception control signal notifies reception of the 
control signal to the home independent base station control section 
through the public reception interface section. Subsequently, the home 
independent base station control section transmits the call waiting 
notification signal to the dual purpose mobile station by using the 
accompanying control channel. The dual purpose mobile station which 
receives the call waiting notification signal causes the dual purpose base 
station control section to recognize the call waiting notification signal 
during indoor self-supporting telephone call. The mobile station executes 
its incoming processing between the public base station and the dual 
purpose mobile station while holding the current telephone call 
temporarily in order to notify the existence of the incoming call to the 
user. By virtue of this operation, the user can respond to the incoming 
call from the public station during the indoor self-supporting telephone 
call. When the dual purpose mobile station detects the response from the 
user, thus holding or disconnecting the indoor self-supporting telephone 
call, it can thus shift to the outdoor public telephone call. When the 
outdoor public telephone call ends, the dual purpose mobile station 
implements the disconnection processing between the public base station 
and the dual purpose mobile station. When the dual purpose mobile station 
is holding the indoor self-supporting telephone call, it can continue the 
indoor self-supporting telephone call by removing the hold state. When the 
dual purpose mobile station is in the disconnection state, it terminates 
the telephone call. 
The above and further objects and novel features of the invention will be 
more fully understood from the following detailed description when the 
same is read in connection with the accompanying drawings. It should be 
expressly understood, however, that the drawings are for purpose of 
illustration only and are not intended as a definition of the limits of 
the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiments of the present invention will now be described in 
detail referring to the accompanying drawings. 
FIG. 10 is a block diagram showing a configuration of a cordless telephone 
system according to the present invention. A home independent base station 
401 of the present invention comprises an antenna 104 for performing 
transmission-reception of radio wave, a transmitter-receiver radio circuit 
103 for executing both demodulation of reception radio waves, and 
modulation of transmission data, a independent base station channel CODEC 
section 102 for executing both decoding of demodulation signals from the 
transmitter-receiver radio circuit 103, and coding of transmission data, a 
call/circuit control section 101 for executing both voice coding of 
received sound signals from fixed network, and voice encoding of 
demodulated voice data from the independent base station channel CODEC 
section 102, and for receiving a call signal from the fixed network, a 
home independent base station control section 105 for executing power 
control among the call/circuit control section 101, the independent base 
station channel CODEC section 102, and the transmitter-receiver radio 
circuit 103, and for executing communication protocol control between the 
independent base station control section 105 and the mobile station 402. 
In addition, there is provided a public reception interface section 105a 
which notifies reception of the call signal to the dual purpose mobile 
station 402 from the public base station 403 in such a way that the public 
reception interface section 105a notifies it using an accompanying control 
channel, a public reception antenna 109 for receiving radio waves 
transmitted from the public base station 403, a reception radio circuit 
108 for executing demodulation of radio waves received from the public 
reception antenna 109, a mobile station reception channel CODEC section 
107 for executing decoding of demodulation signals from the reception 
radio circuit 108, and a public reception control section 106 for 
detecting a call signal of the dual purpose mobile station 402 from among 
the decoded data from the mobile station reception channel CODEC section 
107 in order to notify the public reception interface section 105a. 
Next, FIG. 11 is a block diagram showing the internal configuration of the 
dual purpose mobile station 402 of the present invention. The dual purpose 
mobile station 402 of the present invention comprises an antenna 204 for 
performing transmission-reception of radio waves, a transmitter-receiver 
radio circuit 203 for executing both of demodulation of received radio 
waves and modulation of transmission data, a dual purpose mobile station 
channel CODEC section 202 for executing both decoding of demodulation 
signals from the transmitter-receiver radio circuit 203 and coding of 
transmission data, a speaker 206 for outputting voice audio, a microphone 
207 for inputting voice audio, a telephone call control section 201 for 
executing both voice coding of sound signals received from the microphone 
207 and voice decoding of voice data decoded at the dual purpose mobile 
station channel CODEC section 202, a dual purpose mobile station control 
section 205 for executing power control among the telephone call control 
section 201, the dual purpose mobile station channel CODEC section 202, 
and the transmitter-receiver radio circuit 203, and for executing 
communication protocol control between the dual purpose mobile station 
control section and the home independent base station 401 or between the 
public base station 403 and the same. In addition, there is provided a 
call waiting notification detecting section 205a which is capable of 
detecting notification that a call signal has been transmitted to the dual 
purpose mobile station 402 from the public base station 403 during a 
indoor self-supporting telephone call by means of accompanying control 
channel. 
FIG. 12 is a block diagram showing an operational environment of the 
cordless telephone system of the present invention. The dual purpose 
mobile station 402 is capable of executing the telephone call through the 
home independent base station 401. The dual purpose mobile station 402 is 
further capable of receiving radio waves from the public base station 403. 
When the dual purpose mobile station 402 is in a telephone call state 
through the home independent base station 401, the dual purpose mobile 
station 402 is incapable of receiving radio waves from the public base 
station 403. However, the home independent base station 401 receives radio 
waves from the public base station 403 instead of the dual purpose mobile 
station 402. The home independent base station 401 then causes received 
radio waves at the public reception antenna 109 to be demodulated by means 
of the reception radio circuit 108, decoding the received signal by means 
of the mobile station channel CODEC section 107, detecting the call signal 
by means of the public reception control section 106, and notifying the 
reception to the home independent base station control section 105 through 
public reception interface section 105a. The home independent base station 
401 then transmits the call waiting notification signal 406 to the dual 
purpose mobile station 402 using a accompanying control channel. Thus the 
dual purpose mobile station 402 receives the call waiting notification 
signal. As a result thereof, the dual purpose mobile station 402 is 
capable of receiving the call signal from the public base station 403. 
Next, a first embodiment of the invention will be described referring to 
drawings. 
FIG. 13 is an operational sequence diagram showing the first embodiment of 
the invention. When the public base station 403 transmits call signal 405 
to the dual purpose mobile station during a telephone call 404 currently 
occurring between the home independent base station 401 and the dual 
purpose mobile station 402, the home independent base station 401 receives 
the call signal 405 and transmits the public reception notification 406 to 
the dual purpose mobile station using an accompanying control channel. 
There are two systems in the accompanying control channel. One system is 
capable of transmitting control information without breaking voice 
communication, and another system is capable of transmitting control 
information with breaking voice communication. The present embodiment uses 
the system in which the control information is transmitted without 
breaking the voice communication. When the dual purpose mobile station 402 
receives the control information, it executes its incoming processing 408 
while stopping the telephone call 404 temporarily. The mobile station 402 
transmits a silent transmission requirement to the home base station 401 
(407) in order to cause the home independent base station 401 to perform 
silent transmission. Subsequently, the dual purpose mobile station 402 
stops the telephone call 404 to implement the incoming processing 408. At 
the end of the incoming processing 408, the dual purpose mobile station 
402 transmits a during-telephone call signal (409) to the public station 
403 for notifying that calling of user is in progress. In order to return 
to the telephone call between the dual purpose mobile station 402 and the 
home independent base station, the dual purpose mobile station stops the 
silent transmission to the fixed network. The dual purpose mobile station 
402 returns to the telephone call (412) by transmitting a voice 
transmission restart requirement (410) for transmitting a sound signal, 
and simultaneously transmits (411) a ringing tone to notify reception of 
signal to the user. When the dual purpose mobile station 402 detects 
response from the user, namely detects hooking (413), it executes its 
disconnection processing (414) for disconnecting the indoor 
self-supporting telephone call. When disconnection is completed, the dual 
purpose mobile station 402 shifts therefrom to the telephone call 416 by 
transmitting a response signal 415 to the public base station. When the 
telephone call ends, the dual purpose mobile station returns to the state 
of receive-queuing while executing its disconnection processing 417. 
FIGS. 15, 16 and 17 are flow charts showing operation of the dual purpose 
mobile station according to the first embodiment of the present invention. 
Turning to FIG. 15, when the dual purpose mobile station control section 
205 detects on-hook 302 during a indoor self-supporting telephone call 
301, the dual purpose mobile station proceeds to a telephone call end 
state by executing telephone call disconnection processing 303 which is 
actuated from the side of mobile station 402. When the dual purpose mobile 
station control section does not detect on-hook 302 and receives a 
disconnection signal 304 from the home independent base station 401 the 
dual purpose mobile station also proceeds to the telephone call end state 
337 by executing telephone call disconnection processing 305 which is 
actuated from the independent base station 401. When the dual purpose 
mobile station control section 205 does not receive 304 a disconnect 
signal from the home independent base station 401, but detects a 
hold-manipulation by the user 306, and if the indoor self-supporting 
telephone call is already in a hold state 307, it causes transmission of 
sound signals to be resumed 309 after executing processing 308 to remove 
the holding of the indoor self-supporting telephone call. When the dual 
purpose mobile station control section 205 does not receive 304 a 
disconnection signal from the home independent base station 401, but 
detects a hold-manipulation by the user 306, and if the indoor 
self-supporting telephone call is not on hold 307, it causes silent 
transmission to be executed 311 after executing hold requirement 
processing 310 to cause the hold of the indoor self-supporting telephone 
call. The dual purpose mobile station 402 then rings a hold-melody for 
notifying the during-hold to the user 312. When the dual purpose mobile 
station control section 205 does not detect the hold manipulation by the 
user 306 but detects hook manipulation by the user 313, it executes 
transmission requirement processing 314 of the hooking signal to the home 
independent base station 401. When the dual purpose mobile station control 
section 205 does not detect the hooking manipulation by the user (313), 
but receives 315 a public incoming notification from the home independent 
base station 401, it transmits a silent transmission requirement 316 to 
the home independent base station 401. The dual purpose mobile station 
control section 205 implements the incoming processing 317 with respect to 
the public base station 403 before transmitting a voice transmission 
restart requirement 318 to the home independent base station 401. At this 
time, if the dual purpose mobile station 402 detects the hook manipulation 
319, switching of telephone call is executed (reference number continues 
to FIG. 16). If the dual purpose mobile station 402 does not detect the 
hook manipulation 319, it continues to monitor the hook manipulation until 
ending of a calling period (320). When the calling period ends, the dual 
purpose mobile station 402 resumes the indoor self-supporting telephone 
call. Further, if the dual purpose mobile station does not receive 315 the 
public incoming notification from the home in dependent base station 401, 
the indoor self-supporting telephone call is maintained. 
Next, the operation (telephone call switching operation) after .alpha. of 
FIG. 15 will be explained with respect to FIG. 16. In the first 
embodiment, the telephone call disconnection processing 321 which is 
actuated from the side of the mobile station 402 is executed. The public 
telephone call is started 323 after executing the public response 
processing 322 in which the response from the user is notified to the 
public base station 403. During the public telephone call, if the on-hook 
is detected 324, the telephone call disconnection processing 325 is 
executed which is actuated from the mobile station 402, and the process 
proceeds to the telephone call end state 337. If the disconnection signal 
is received 326 from the home independent base station 401 without 
detecting the on-hook, the telephone call disconnection processing is 
executed 327 which is actuated from the home independent base station 401, 
and the process proceeds to the telephone call end state 337. When the 
dual purpose mobile station 402 does not receive 326 a disconnection 
signal from the home independent base station 402, but detects 
hold-manipulation by the user 328, and if the indoor self-supporting 
telephone call is already in the hold state 329, transmission of sound 
signal is resumed 331 after executing processing 332 to remove the hold of 
the indoor self-supporting telephone call. If the dual purpose mobile 
station 402 is not holding an indoor self-supporting telephone call 329, 
processing of the hold of the indoor self-supporting telephone call is 
executed 332, causing silent transmission 333, and ringing a hold-melody 
for notifying the user of the hold 334. If the dual purpose mobile station 
402 does not detect the hold-manipulation by the user, but detects a 
hooking operation (335), a hooking signal is transmitted 336 to the public 
base station 403. If the dual purpose mobile station 402 does not detect 
the hook manipulation, the outdoor public telephone call is maintained. 
Next, the second embodiment of the invention will be described with respect 
to FIG. 14. 
FIG. 14 is operational sequence diagram showing operation of the second 
embodiment of the present invention. During telephone call 404 between the 
home independent base station 401 and the dual purpose mobile station 402, 
when the public base station 403 transmits call signal (405) to the dual 
purpose mobile station, the home independent base station receives the 
call signal 405 in order to transmit the public incoming notification 406 
to the dual purpose mobile station using accompanying control channel. 
When the dual purpose mobile station receives the notification 406, it 
transmits a silent transmission requirement 407 to the home independent 
base station 401 in order to execute silent transmission while temporarily 
stopping the telephone call 404. Subsequently, the dual purpose mobile 
station 402 executes the incoming processing 408. At the end of the 
incoming processing 408, the dual purpose mobile station 402 transmits the 
during-call signal 409 notifying the public station 403 that the telephone 
call 404 is in progress. In order to return to the telephone call between 
the home independent base station 401 and the dual purpose mobile station 
402, the dual purpose mobile station 402 stops silent transmission to the 
fixed network, thus returning to the telephone call 412 by transmitting 
the voice transmission restart requirement 410 in order to transmit the 
sound signal. Simultaneously, the dual purpose mobile station 402 
transmits the ringing tone for notifying the user 411 of the incoming 
call. If the user's response namely hooking 413 is detected, the 
hold-requirement 418 is transmitted to the home independent base station 
401 to hold the indoor self-supporting telephone call. The dual purpose 
mobile station 402 shifts to the new telephone call 416 after being 
notified of the setting of the hold state 419 from the home independent 
base station 401. When the telephone call 416 is terminated, the 
disconnection processing 417 is executed. Further, in order to return to 
the indoor self-supporting telephone call again while removing the hold, 
the dual purpose mobile station 402 executes hold-removing recall out 
processing 420 to resume the indoor self-supporting telephone call (421). 
When the telephone call is terminated, the dual purpose mobile station 402 
executes disconnection processing 422 to return to the state of the 
incoming queuing. 
FIGS. 15 and 17 are flow chart diagram showing operation of the dual 
purpose mobile station control section 205 according to the second 
embodiment of the present invention. The operation of the dual purpose 
mobile station control section 205 depicted in FIG. 15 and described above 
with respect to the first embodiment is the same operation performed in 
the second embodiment and shall not be reiterated. 
The operation (telephone call switching operation) after .alpha. of FIG. 15 
will be described with respect to FIG. 17. In the second embodiment, in 
order to perform holding of the indoor self-supporting telephone call, the 
dual purpose mobile station 402 executes hold requirement processing 338 
to the home independent base station 401, and executes incoming processing 
339 to the public base station 403, before starting the public telephone 
call 340. During the public telephone call, if the on-hook is detected 
341, the dual purpose mobile station 402 executes the telephone call 
disconnection processing 342 which is actuated from the mobile station 
402. The dual purpose mobile station 402 returns to the indoor 
self-supporting telephone during call state 337 after executing hold 
removal re-call out processing 343 for resuming the telephone call by 
removing the hold. If the dual purpose mobile station 402 does not detect 
the on-hook 341, but receives 344 a disconnection signal from the home 
independent base station 401, the telephone call disconnection processing 
is executed 345 which is actuated from the independent base station 401. 
The dual purpose mobile station 402 proceeds to the during indoor 
self-supporting telephone call state 337 after executing the hold removal 
re-call out processing 343 for resuming telephone call by removing the 
hold. If the dual purpose mobile station 402 does not receive 344 the 
disconnection signal from the home independent base station 401, but 
detects hold manipulation by the user, and if the indoor self-supporting 
telephone call is already on-hold 347, transmission of sound signals is 
restarted 349 after executing processing 348 which removes the hold of the 
indoor self-supporting telephone call. If the indoor self-supporting 
telephone call is not on hold 347, the processing 350 is executed that 
causes the indoor self-supporting telephone call to be put on hold. Silent 
transmission is begun 351, before ringing a hold-melody in order to notify 
the hold state to the user 352. If the dual purpose mobile station 402 
does not detect the hold manipulation by the user 346, but detects the 
hook manipulation 353, the hooking signal is transmitted 354 to the public 
base station 401. The dual purpose mobile station 402 maintains the 
outdoor public telephone call unless the hooking manipulation is detected. 
Operation of the home independent base station control section 105 common 
to the above described first and the second embodiments will be described 
with reference to FIG. 18. 
FIG. 18 is a flow chart showing operation of the indoor self-supporting 
telephone call of the home independent base station control section 105 
according to the present invention. When the home independent base station 
control section 105 receives a disconnection signal 356 during the period 
of the indoor self-supporting telephone call state 355, it proceeds to 
indoor self-supporting telephone call end state 371 after executing the 
telephone call disconnection processing 357 which is actuated from the 
mobile station 402. If the home independent base station control section 
105 does not receive the disconnection signal 356, but detects line 
disconnection 358, it proceeds to the indoor self-supporting telephone 
call end state 371 after executing telephone call disconnection processing 
359 which is actuated from the independent base station 401. If the home 
independent base station control section does not detect the line 
disconnection 358, but receives 360 a hold requirement from the dual 
purpose mobile station 402, the processing 361 is executed which causes 
the indoor self-supporting telephone call to be put on hold, causes silent 
transmission 362, and rings the hold-melody in order to notify the hold 
state to the user 363. If the home independent base station control 
section 105 does not receive the hold requirement 360 from the dual 
purpose mobile station 402, but receives a hold removal requirement 364, 
transmission of sound signal is restarted 366 after executing the 
processing 365 which removes the hold state of the indoor self-supporting 
telephone call operation. If home independent base station control section 
105 does not receive the hold removal requirement 364 from the dual 
purpose mobile station, but receives a hooking signal transmission 
requirement 367, the hooking signal is transmitted 368. If the home 
independent base station control section 105 does not receive the hooking 
signal transmission requirement 367 from the dual purpose mobile station 
402, but receives 369 a call signal from the public base station 403 to 
the dual purpose mobile station 402, a public incoming notification 
transmission is sent to the dual purpose mobile station 402 by 
accompanying control channel 370. 
As described above, in accordance with the present invention, the home 
independent base station is provided with the public reception control 
section, the mobile station reception channel CODEC section, the reception 
radio circuit, the public reception antenna, and the public reception 
interface section. The home independent base station receives the call 
signal transmitted from the public base station intended for the dual 
purpose mobile station. The call waiting notification signal is then 
transmitted to the dual purpose mobile station 402 by means of 
accompanying control channel. The mobile station is thus capable of 
receiving notification from the public base station 403 due to the fact 
that the dual purpose mobile station receives the call waiting 
notification signal from the home base station 401. Consequently, the user 
of the dual purpose mobile station 402 can respond to the incoming call 
from the public base station within the area where it is capable of 
receiving both radio waves both of the public base station and the home 
independent base station during a indoor self-supporting telephone call. 
Further, the home independent base station 401 is provided with the public 
reception control section, the mobile station reception channel CODEC 
section, the reception radio circuit, the public reception antenna, and 
the public reception interface section. The home independent base station 
401 transmits the call waiting notification signal to the dual purpose 
mobile station 402 by means of the accompanying control channel after 
receiving the call signal transmitted from the public base station 
intended for the dual purpose mobile station 402. The dual purpose mobile 
station 402 receives the call waiting notification signal so that the user 
can recognize the incoming call from the public base station 403. If the 
user responds thereto, it is capable of shifting to the outdoor public 
telephone call by executing incoming processing between the public base 
station 403 and the dual purpose mobile station 402 while the dual purpose 
mobile station 402 causes the indoor self-supporting telephone call to 
temporarily be put in a hold state. Consequently, when there is a 
telephone call from the public base station during a indoor 
self-supporting telephone call, the user can shift to the outdoor public 
telephone call, while disconnecting or holding the indoor self-supporting 
telephone call. 
While preferred embodiments of the invention have been described using 
specific terms, such description is for illustrative purpose only, and it 
is to be understood that changes and variations may be made with out 
departing from the spirit or scope of the following claims.