Radio telephone system control apparatus and method

Abstract: In a radio telephone system control apparatus and method, the radio telephone sets 5,5' are arranged to receive a paging signal intermittently and at different periods of time to one another. A master apparatus 4 sends a paging signal to the radio telephone sets 5,5'. A radio telephone set 5' which receives the paging signal responds and the master apparatus 4 sends a channel designating signal when it receives the paging response signal. The radio telephone set 5' which has previously sent the paging response signal then switches to the designated channel on receiving the channel designating signal. The remaining radio telephone set(s) 5, which did not receive the paging signal are set to a wait state on receiving the channel designating signal.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a radio telephone system control apparatus and a method for controlling the connection of a master apparatus connected to wired telephone channel and a plurality of radio telephone sets connected to the master apparatus through radio channels with the master apparatus, and more particularly an apparatus for controlling the connection in response to a paging made through lines for wired telephone sets. 2. Description of the Related Arts Among radio telephone systems comprising a master apparatus connected to wired telephone channels and one or more radio telephone sets connected to the master apparatus through radio channels may be mentioned a so-called cordless telephone apparatus, for example c.f. Kawasaki, R.: Cordless Telephone Using Multi-Channel-Access Technique; Japan Telecommunication Review, Vol. 26, No. 2 April 1984, Tokyo J.P pages 101-105. The cordless telephone apparatus is constituted by a master apparatus connecting apparatus connected to wired telephone channels, and a wireless telephone set provided for the master apparatus in a one to one correspondence, and the frequencies of its signals are fixed such that up radio channels from the radio telephone sets to the master apparatus utilizes signals of frequency f 1 , while down telephone channels from the master apparatus to the radio telephone sets utilize signals of frequency f 2 . As a consequence, where two radio telephone sets are utilized, it is necessary to install two master apparatus. With such a radio telephone system utilizing two radio telephone sets and two master apparatus, however, two radio telephone sets are not usually used simultaneously, so that provision of two master apparatus is not economical. In recent years, for the purpose of efficiently utilizing allocated frequencies, a so-called multi-channel access system has been adopted wherein a frequency being used is determined by utilizing a common channel, for example, a control channel between a plurality of master apparatus, and then the channel is switched to a speech channel corresponding to the frequency. However, when such multi-channel access system is adopted, there is a problem in the case where a master apparatus is provided for each of the two radio telephone sets that a paging is made from a wired telephone set, the two master apparatus start connection control using respective control channels simultaneously, whereby radio waves from these control channels interface with each other. Thus, the connection control is sometimes made impossible. SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a radio telephone system control apparatus and a method which enables a connection control for a plurality of radio telephone sets with a single master apparatus as well as transferring from a radio telephone set in which a speech is being made to other radio telephone sets. According to one aspect of this invention, there is provided a radio telephone system control apparatus comprising a plurality of radio telephone sets, each having a slave radio set; a master apparatus connected to a wired telephone channel for exchanging signals between the master apparatus and the slave radio sets of said telephone sets; means provided for said master apparatus for detecting a paging through said wired telephone channel; means for sequentially sending, with a predetermined time difference, paging signals each containing a channel designating signal to the slave radio sets of said plurality of radio telephone sets from the master radio set of said master apparatus when said paging is detected; means responsive to the received paging signal for sending a paging response signal to the master radio set of said master apparatus from the slave radio sets of said radio telephone sets, and for switching the radio channel of the slave radio sets of said radio telephone sets to a radio channel corresponding to said channel designating signal, means for switching the radio channel of said master radio set of said master apparatus to a radio channel corresponding to said channel designating signal when said paging response signal is received within a predetermined interval after sending out said paging signal from the master radio set of said master apparatus Whereby the connection control between said wired telephone channel and either one of said plurality of radio telephone sets based on the paging via said wired telephone channel is effected by a single master apparatus. According to a modified embodiment of this invention, there is provided a radio telephone system control apparatus comprising a plurality of radio telephone sets, each having a slave radio set; master apparatus connected to a wired telephone channel for exchanging signals between the master apparatus and the slave radio sets of said radio telephone sets; means provided for said master apparatus for detecting a paging through said wired telephone channel; means for sending paging signal to the slave telephone sets of said radio telephone sets from the master radio set of said master apparatus when said paging is detected by said detecting means; means for sending a paging response signal to the master radio set of said master apparatus from the slave radio set of said radio telephone set in response to said paging signal; means responsive to said paging response signal for sending a channel designating signal to the slave radio set of said radio telephone set from the master radio set of said master apparatus; means for switching the radio channel of the master radio set of said master apparatus to a radio channel corresponding to said channel designating signal; means responsive to said channel designating signal for switching a radio channel of the slave radio set of said radio telephone set to a radio channel corresponding to said channel designating signal, thereby effecting connection control between said wired telephone channel and either one of said plurality of radio telephone sets based on the paging through said wired telephone channel with a single master apparatus. According to another embodiment of this invention, there is provided radio telephone system control apparatus comprising a plurality of radio telephone sets, each having a slave radio set; master apparatus connected to a wired telephone channel for exchanging signals between the slave radio sets of said radio telephone set and said master apparatus; means responsive to a predetermined transfer operation for sending a transfer address designation signal to the master radio set of said master apparatus from a slave radio set of said radio telephone set subjected to a transfer operation; means responsive to a reception of said transfer address designating signal for sending a paging signal to the slave radio set of an addressed radio telephone set from the master radio set of said master apparatus; means responsive to a receival of said paging signal for sending a paging response signal to the master radio set of said master apparatus from the slave radio set of said transfer addressed radio telephone set; means responsive to a receival of said paging response signal for sending a bell ringing signal to the slave radio set of said radio telephone set from the master radio set of said master apparatus; means provided for said radio telephone set for producing a call tone for sending an off-hook signal to the radio telephone set of said master apparatus from the slave radio set of said transfer addressed radio telephone set when said transfer addressed radio telephone set hooks off; and means responsive to said off-hook signal for the slave radio set of a radio telephone set which has issued a transfer signal from the master radio set to said master apparatus, thereby substituting said radio telephone set which has issued said transfer signal with said wired telephone channel and said transfer address radio telephone set which has sent out said off-hook signal. According to another aspect of this invention, there is provided a method of controlling a radio telephone system of the type wherein the connection of a wired telephone channel and a plurality of radio telephone sets is controlled by a single master apparatus connected to said wired telephone channel, said method comprising the steps of; detecting a paging through said wired telephone set; sequentially sending, with a predetermined time difference, a paging signal to said plurality of radio telephone set from said master apparatus when said paging is detected; connecting a radio channel of said master channel and a radio channel of said radio channel to the same channel when either one of said radio telephone response to said paging signal; and establishing a speech channel between a radio telephone set responded to said paging signal and a wired telephone channel connected to said master apparatus. According to a modification, there is provided a method of controlling a radio telephone system of the type wherein a connection between a wired telephone channel and a plurality of radio telephone sets is controlled by a single master apparatus connected to said wired telephone channel, said method comprising the steps of: detecting a paging through said wired telephone channel; sending a paging signal to said radio telephone set from said master apparatus when said paging is detected; sending a paging response signal to said master apparatus from said radio telephone set in response to said paging signal; sending a channel designating signal to said radio telephone set from said master apparatus in response to said paging response signal; switching a radio channel of said master apparatus to a radio channel corresponding to said channel designating signal; switching a radio channel of said radio telephone set to a radio channel corresponding to said channel designating signal in response to said channel designating signal; and establishing a speech channel between a radio telephone set responded to said paging signal and said wired telephone channel connected to said master apparatus. According to another modification, there is provided a radio telephone system control method of the type wherein a connection between a wired telephone channel and a plurality of radio telephone sets is controlled by a single master apparatus, said method comprising the steps of: sending a transfer address designating signal to the master radio set of said master apparatus from a radio telephone set which has sent out a transfer signal in response to a predetermined transfer operation; sending a paging signal to a transfer address radio telephone set from said master apparatus when said transfer address designating signal is received; sending a paging response signal to the master radio set of said master apparatus from said transfer address radio telephone set when said paging signal is received; and connecting the transfer address telephone set responsive to said paging signal to said wired telephone channel connected to said master apparatus instead of a radio telephone set which has operated to send a transfer signal. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig.1 is a block diagram showing the detail of one embodiment of this invention; Figs.2 through 6 show flow charts showing the operation of the embodiment shown in Fig.1; DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the radio telephone system according to this invention shown in Fig.1 comprises one master apparatus 4 and two radio telephone sets 5 and 5'. For the purpose of simplifying the description, only two radio telephone sets are shown but it will be clear that the invention is also applicable to three or more radio telephone sets. The master apparatus 4 is connected to a wired telephone channel, not shown, through a terminal 3. A signal from the wired telephone channel inputted to terminal 3 is supplied to a transmitter 16 via a line relay 23 and a hybrid circuit 22, while the output from the transmitter 16 is sent out from an antenna 12 via an antenna duplexer 13. On the other hand, a signal received by antenna 12 is applied to a receiver 14 through antenna duplexer 13, and the output from the receiver 14 is supplied to the wired telephone channel via hybrid circuit 22, line relay 23 and terminal 3. A synthesizer 21 is provided for determining the radio frequency of the transmitter 16 and the receiver 14, and a control unit 15 is provided for the purpose of controlling transmitter 16, receiver 14 and synthesizer 21. Read only memory devices (ROM) 18 and 18' are provided for the purpose of storing identification information for controlling the connections to radio telephone sets to be described later, the identification information being used in the control unit 15. The radio telephone sets 5 and 5' are connected to the master apparatus through wireless channels. The wireless telephone sets 5 and 5' have the same construction except that their ROMs 17 and 17' store different information. More particularly, element 6 bounded by dotted lines in Fig.1 has the same construction for both telephone sets 5 and 5' so that in the following description, elements utilized in radio telephone set 5' are designated by the same reference numberals as those used in the radio telephone set 5 except addition of a prime. The signal transmitted from the master apparatus is received by an antenna 11 and applied to a receiver 19 through an antenna duplexer 10, and the output of the receiver 19 is supplied to a handset or loudspeaker 29 to be connected to generate sound. A signal inputted to a microphone 30 is sent to the master apparatus 4 via transmitter 8, antenna duplexer 10, and antenna 11. A synthesizer 20 is provided for determining the radio frequency of receiver 19 and transmitter 8, while a control unit 9 is provided for controlling receiver 19, transmitter 8 and synthesizer 20. A loudspeaker 31 connected to the synthesizer produces a call tone. A hook switch 7 is provided to effect an origination and to respond to the call tone produced by the loudspeaker 31. The information stored in ROMs 17 and 17' corresponds to that stored in ROMs 18 and 18' of the master apparatus 4. This embodiment employs a multichannel access system comprising a single control channel (C-CH) and a plurality, for example 45, of speech channels. Thus a speech channel is established by commonly utilizing a single control channel by a plurality of apparatus. The operation of this embodiment will be described with reference to the flow charts shown in Figs. 2 through 6. Fig. 2 shows a flow chart for the case when an origination is issued from radio telephone set 5. At step 201, when the hook switch 7 of the radio telephone set 5 is hooked off at step 202, this state change is detected by control unit 9 and this unit 9 turns ON the transmitter 8, and then at step 203 the originating signal is sent to the master apparatus 4 via antenna duplexer 10 and antenna 11. The transmission of the originating signal from the radio telephone set 5 to the master apparatus 4 is made by using the control channel (C-CH). Upon termination of the transmission of the originating signal, at step 204, the control unit 9 turns off the transmitter 8. At step 205, the master apparatus 4 receives with receiver 14 the originating signal via antenna 12 and antenna duplexer 13 and the demodulated output from the receiver 14 is applied to the control unit 15. Then at step 206, the control unit 15 turns ON transmitter 16 for transmitting a call signal to radio telephone set 5' at step 207. The transmission of the call signal from the master apparatus 4 to the radio telephone set 5' is performed by using the control channel (C-CH). For the purpose of selectively sending the call signal to the radio telephone set 5', an identifying information is incorporated into the call signal stored in the ROM 18'. When the radio telephone set 5' receives the call signal, it compares the identifying signal contained in the call signal with the information stored in ROM 17', and when they coincide with each other, the radio telephone set 5' accepts the call signal. In the following, a digit '2' shows a signal containing the identifying signal stored in ROM 18', while a digit '1' shows a signal containing an identifying signal stored in ROM 18. An identifying signal stored in ROMs 18, 18', 17 and 17' is made up of a identifying code common to both radio telephone sets 5 and 5' and individual identifying codes assigned to respective radio telephone sets 5 and 5'. The common identifying code is used to identify the other radio telephone set. At step 208, the radio telephone set 5' receives a call signal 2 transmitted from the master apparatus 4 by receiver 19' through antenna 11' and antenna duplexer 10'. The demodulated output from receiver 19' is supplied to control unit 9' whereby it turns ON transmitter 8' at step 209, and a call response signal 2 is sent to the master apparatus 4 at step 210. As has been pointed out before, the call response signal 2 contains an identifying signal stored in ROM 17'. Upon termination of the call response signal 2, at step 211, the control unit 9' of the radio telephone system 5' turns OFF transmitter 8'. After sending the call signal 2 at step 207, at step 212 the master apparatus 4 executes a judgment as to whether a predetermined time has elapsed or not. When the result of judgment shows that the predetermined time has not yet elapsed, that is not time out, the program is transferred to step 213 at which a judgment is made as to whether receiver 14 has received a call response signal 2 from radio telephone set 5' or not. When the result of judgment at step 213 is NO, the program is returned to step 212. When result of judgment at step 212 shows a time out and when the result of judgment at step 213 shows a receival of a call response signal 2, the program is transferred to step 214. More particularly, when a predetermined time has elapsed after sending out a call signal 2 from the master apparatus 4, or when a call response signal 2 is received from radio telephone set 5', the program is transferred to step 214. At step 214, a channel designating signal 1 for designating a predetermined channel is transmitted to radio telephone set 5 by using the control channel. At step 215, the radio telephone set 5 executes a judgment as to whether the radio telephone set 5 has received the channel designating signal 1 or not. When the result of judgment is YES, the control unit 9 controls the synthesizer 20 for switching the radio frequency of transmitter 8 and receiver 19 to that corresponding to a predetermined speech channel (S-CH 1 ) at step 216. After that, at step 217 a timer is operated and after a predetermined time, the transmitter 8 is turned ON at step 218. Following the transmission of the channel designating signal at step 214, at step 219, the master apparatus 4 sends out a channel designating signal 2 to radio telephone set 5' by using the control channel. The channel designating signal 2 designates the same speech channel as the channel designating signal 1. Upon completion of the transmission of the channel designating signal, at step 220, the master apparatus 4 turns OFF transmitter 16 so as to control the synthesizer 21, thereby switching the transmission/reception frequency to that corresponding to speech channel (S-CH 1 ) and then turning ON transmitter 16 at step 222. As a consequence, speech between the master apparatus and the radio telephone set 5 becomes possible by utilizing the speech channel (S-CH 1 ). At step 223, in radio telephone set 5' a judgment is made as to whether the channel designating signal 2 sent from the master apparatus 4 has been received or not. When the result of judgment executed at step 223 is YES, the program is advanced to step 224 at which the transmission/reception frequency is switched to that corresponding to speech channel (S-CH 1 ) and at step 235, the state is changed to a waiting state. Under this state since the transmitter 8' at the radio telephone set 5' is OFF, the radio telephone set 5' can receive only a signal from the master apparatus 4 utilizing speech channel (S-CH 1 ). After turning ON the transmitter 8 at step 218, the radio telephone set 5 turns ON the audio frequency circuit of the transmitter 8 and receiver 19 at step 226. At step 222, the master apparatus turns ON transmitter 16 and turns ON line relay 23 at step 227 for closing a relay contact, whereby radio telephone set 5 can make speech through a wired telephone channel connected to terminal 3 of the master apparatus 4 by using a handset 29 and microphone 30. In this state, when the hook switch 7' of the radio telephone set 5' now in the waiting state is hooked OFF, the reception of the speech is possible but transmission thereof is impossible. The operation of a case wherein a paging is made to the master apparatus from the wired telephone channel will be described as follows. Fig. 3 shows a flow chart showing the operation of a case in which the paging is made to the master apparatus from a wired telephone channel. The detection of the paging is made by judging the presence or absence of the paging by the control unit 15 based on the output signal of a detecting circuit, not shown, connected to the wired telephone channel. At step 301, when a paging is made to the master apparatus, in other words, when the same is called by the wired telephone channel, at step 302 the master apparatus turns ON the transmitter 16 so as to send out a paging signal containing a designating signal that designates a predetermined speech channel at step 303. The paging signals are sent to respective radio telephone sets in a predetermined order of priority which is determined by the order of inserting IC sockets into ROMs 18 and 18' or by the order of information prestored in ROMs 18 and 18'. The order of priority may be set by an independent switch or the like, or may be randomly set by generating a suitable random number. Further, the order of priority can be set according to the hysteresis of the connection to the wired telephone channel. Thus, for example, the lastly used radio telephone set or a radio telephone set most frequently used can be set to the upper most order. In the flow chart shown in Fig. 3, the radio telephone set 5 is a higher order of priority than the radio telephone set 5'. Thus, at step 303, a paging signal 1 is sent to radio telephone set 5 . At step 304, when the radio telephone set 5 receives the paging signal 1, transmitter 8 is turned ON at step 305, and a paging response signal 1 is sent to the master apparatus at step 306. The master apparatus 4 monitors the paging response signal 1. When the paging signal is received within a predetermined interval after sending out the paging signal 1 at step 303. More particularly, at step 307, when it is judged that there is no time out, and at step 308, when it is judged that the paging response signal 1 has been received, the program is transferred to step 309 for turning OFF receiver 16. Then at step 310, a radio channel is switched to a speech channel (S-CH 2 ). After that at step 311, the transmitter 16 is turned ON. At step 306, upon termination of the transmission of the paging response signal 1, at step 312, the radio telephone set 5 turns OFF transmitter 8 to switch the radio channel to the speech channel (S-CH 2 ). After that, at step 314, transmitter 8 is turned ON again, thereby establishing speech channel between master apparatus and radio telephone set 5 by utilizing the speech channel (S-CH 2 ). At step 311, the master apparatus turns ON transmitter 16 and then at step 315, the master apparatus sends out a bell ringing signal by using the speech channel (S-CH 2 ). At step 319 as the radio telephone set 5 receives the bell ringing signal, at step 320, call tone is produced from loudspeaker 31. At step 318 when the hook switch 7 is hooked off in response to the call tone, at step 321, an off-hook signal is sent to the master apparatus 4 through the speech channel (S-CH 2 ). Then at step 322, the audio frequency circuit is turned ON. At step 316 when the master apparatus receives the off-hook signal from the radio telephone set, at step 317, the line relay 23 is turned ON, whereby the radio telephone set 5 can exchange speech with a wired telephone channel through the master apparatus 4. At step 307, when time out is judged, that is where a paging response signal 1 is not returned from the radio telephone set after elapse of a predetermined interval, after sending out of the paging signal, at step 323 a paging signal 2 for the radio telephone set at the next order of priority is sent out. At step 324, when the radio telephone set 5' receives the paging signal 2, at step 325, the transmitter 8' is turned ON to send out the paging response signal 2 at step 326. When this paging response signal 2 is received by the master apparatus 4 within a predetermined interval after sending out the paging signal 2, the program is transferred to step 309 at which the transmitter 16 is turned OFF, and then the channel is switched to speech channel (S-CH 2 ), whereby the transmitter 16 is turned ON again to send out a bell ringing signal at step 315. After sending out the paging response signal 2, the radio telephone set 5' executes the same operations as the radio telephone set 5 with respect to a portion 24 of the flow chart bounded by dotted lines. More particularly, transmitter 8' is turned OFF first for switching the speech channel (S-CH 2 ) and turning ON again the transmitter 8'. When a bell ringing signal is received from the master apparatus, a call tone is sent out. When the hook switch 7' is off-hooked in response to the call tone, an off-hook signal is sent out and then the audio frequency circuit is turned ON. At step 316, when the master apparatus receives an off-hook signal from radio telephone set 5', at step 317, the line relay is turned ON so as to connect the radio telephone set 5' to the wired telephone channel via the master apparatus. When the time out is judged at step 327, that is when no paging response signal 2 is sent back from radio telephone set in a predetermined interval even though a paging signal 2 has been sent out, the program is transferred to step 329, thus bringing the master apparatus to the waiting state. Fig. 4 shows another flow chart in a case where a paging is made to the master apparatus from a wired telephone channel. As can be noted from this flow chart, radio telephone sets 5 and 5' intermittently receive signals at different periods and the master apparatus sends a paging signal containing only the common identifying code. When either one of the radio telephone sets 5 and 5' (in the flow chart telephone set 5') respond to the paging signal, both radio telephone sets 5 and 5' are connected to the predetermined speech channel (S-CH 2 ) so as to cause the telephone set 5' to generate a call tone and the telephone set 5' which became off-hook state in response to the call tone is connected to the wired telephone channel, whereas the radio telephone set 5 is brought to the waiting state. At step 401 when there is a call from the wired channel, at step 402, the master apparatus 4 turns ON transmitter 16 for transmitting a paging signal over the control channel (C-CH) at step 403. As above described, the paging signal contains only the common identifying code. In a condition when radio telephone sets 5 and 5' do not receive any signal, they intermittently receive the signal at a predetermined period (battery saving operation). More particularly, at step 404, radio telephone set 5 turns OFF receiver 19 and as the set time of the timer 1 elapses it turns ON receiver 19 at step 405. On the other hand, at step 407 where there is no received signal and the set time of timer 2 has elapsed at step 408, the receiver 19 is turned OFF again. In the same manner, at step 409 radio telephone set 5' turns OFF receiver 19'; and as the set time of time 3 has elapsed at step 410, the receiver 19' is turned ON. At step 412 where there is no signal received, and at step 413 the set time of timer 4 has elapsed, the receiver 19' is turned OFF again. Suppose now that a paging signal transmitted from master apparatus 4 at step 403 is received by radio telephone set 5' and that the receival is judged at step 412. In this case, the program is transferred to step 414 so as to make a judgment as to whether the received signal is a paging signal or not. When the signal is the paging signal, at step 415, transmitter 8' is turned ON for sending out a paging response signal at step 416 and for turning OFF the transmitter 417 at step 417. When the paging response signal is received by the master apparatus 4 at step 419 in a predetermined interval after sending out the paging signal at step 403, the master apparatus 4 sends out a channel designating signal that designates a predetermined speech channel at step 420. After that, at step 421, transmitter 16 is turned OFF. When the radio telephone set 5' receives the channel designating signal at step 423 in a predetermined interval after sending out the paging response signal at step 416, and when the received signal is judged as the channel designating signal at step 422, the program is transferred to the flow chart shown by dotted line block 24. This flow chart is the same as the flow chart in block 24 shown in Fig. 3. At step 407, the channel designating signal transmitted from the master apparatus 4 is judged by radio telephone set 5, and then the program is transferred to step 424. In this case, since the signal is not the paging signal, after switching the channel to speech channel (S-CH 3 ) at step 425, and the telephone set is brought the waiting state at step 426. At step 421, after turning OFF transmitter 16, the master apparatus switches the channel to the speech channel (S-CH 3 ) at step 427 and then the program is transferred to the flow chart shown by block 25. The flow chart shown by this block 25 is the flow chart shown by block 25 in Fig, 3. In Fig. 4, two flow charts shown by each of blocks 26 and 27 are the same, respectively. Fig. 5 shows a flow chart where a paging is made from the wired telephone channel. The flow chart shown in Fig. is a flow chart after the master apparatus 4 and the radio telephone sets 5 and 5' are connected to the same speech channel in the same manner as the flow chart shown in Fig. 4. At step 501, the master apparatus 4 judges as to whether there is a paging, that is a call signal from the wired telephone channel. When it is judged that there is a call signal, at step 502, a bell ringing signal is sent out, whereas when it is judged that there is no call signal, at step 503, a bell non-ringing signal is sent out. Whether the bell ringing signal is received or not is judged by radio telephone set 5, for example at step 504. At step 505, when it is judged that the received signal is the bell ringing signal, a call tone signal is sent out at step 506, and the hook switch 7 is hooked OFF at step 507 in response to the call tone. Then, transmitter 8 is turned ON at step 508 to send out an off-hook signal at step 509 which is received by master apparatus 4 at step 510, whereby the master apparatus 4 turns ON the line relay 23 at step 511. At step 509, after sending out the off-hook signal, the radio telephone set 5 turns ON the audio frequency circuit at step 512, thus establishing a speech state at step 513. At step 505, when it is judged that the bell ringing signal is not received, and at step 507, when it is judged that the hook switch is ON at step 507, that is when it is judged that the hook switch is not OFF, the program is returned to step 504. At step 510, when it is judged that an OFF hook signal is not yet received, the program is returned to step 501. At step 504, when it is judged that no signal is received, the program is returned to step 514 to bring the state to the waiting state. More particularly, with the flow chart shown in Fig. 5, when there is a paging through a wired telephone channel, both radio telephone sets 5 and 5' generate a call tone signal so that firstly off-hooked radio telephone set becomes a speech state, while the other radio telephone set becomes the waiting state because there is no signal received. In this case, by using only the bell ringing signal the circuit is made to the waiting state when the bell ringing signal does not arrive for a predetermined interval. Fig. 6 shows radio telephone period transfer operations of the radio telephone system according to this invention. Suppose now that the radio telephone set is talking whereas the radio telephone set 5' is in the waiting state. Under these states, when transfer switch 32 of the radio telephone set 5 is turned ON, at step 601 it is judged that there is a transfer request so that at step 602, the radio telephone set 5 sends out a signal 2 (connecting signal) designating a telephone set to which the radio telephone period is to be transferred (herein after turned a transfer address). It should be understood that the transfer address designation signal contains an identifying information that identifies radio telephone set 5', that is the transfer address. At step 603, when the master apparatus 4 receives the transfer address signal 2, the program is transferred to step 604 for preserving an office line being used. Then at step 605, a paging signal 2 is sent to radio telephone set 5' to which the transfer is to be made by using a speech channel (S-CH 1 ). At step 607, when the radio telephone set 5' receives the paging signal 2, the program is transferred to step 608 at which transmitter 8' is turned ON. Then at step 609, the paging response signal 2 is sent back to the master apparatus 4 through speech channel (S-CH 1 ). At step 610, the master apparatus detects the paging response signal 2 from the radio telephone set 5' and then at step 611, a bell ringing signal 2 is sent to the radio telephone set 5' through speech channel S-CH 1 . At step 612, when the radio telephone set 5' detects the reception of the bell ringing signal 2, it sends out a call tone signal at step 613. When the telephone set of a called party becomes an off-hook state at step 614, the program is transferred to step 615 at which an off-hook signal is sent to the master apparatus through speech channel (S-CH 1 ). Then at step 616, the audio frequency circuit of receiver 19' is turned ON. At step 617, when the master apparatus 4 detects the receival of the off-hook signal from the radio telephone set 5', at step 617 a transfer termination signal 1 is sent to radio telephone set through the speech channel (S-CH 1 ). At step 602, after the radio telephone set 5 sends out a transfer address signal 2, and then at step 619, transmitter 8' is turned ON. Then at step 620, a transfer lamp 33 is lighted to inform that the signal is now being transferred. At step 621, when radio telephone set 5 detects the transfer termination signal 1 sent from the master apparatus 4, at step 622, the transfer lamp is extinguished. Then the program is transferred to step 622 to extinguish the transfer lamp 33, and at step 623, the state is brought to the waiting state. At step 618, after the main apparatus 4 has transmitted the transfer termination signal 1, the preservation of the used office line is released at step 624, thus completing the transfer of the signal from radio telephone set 5 to radio telephone set 5' to enable radio telephone set 5' to speak. Although the embodiment shown in Fig. 6 is constructed such that the master apparatus 4 waits to operate until a paging response signal from the transfer address radio telephone apparatus, that is, the radio telephone set 5', and an off-hook signal 2 are received, it is also possible to construct such that the radio telephone set 5', that is, the transfer address telephone set monitors the paging response signal 2 and the off-hook signal 2' from the radio telephone set 5' and to send out a transfer impossible signal or a bell ringing signal to the radio telephone set 5 requesting a transfer, when the paging response signal 2 and the off-hook signal 2 are not sent back from the radio telephone set 5' even when the predetermined interval has elapsed. Alternatively, it is also possible to construct such that the radio telephone set 5 requesting transfer monitors a transfer termination signal sent back from the master apparatus 4 and to automatically generate an alarm tone when the transfer termination signal is not sent back from the master apparatus even when the predetermined interval has elapsed, thus disenabling transfer which urges the transfer operator to hook OFF so as to establish an office line connection. Although in the foregoing embodiments, pair of transmitter and receiver was used as the master apparatus, a plurality of pairs of the transmitters and receivers can also be used. Further, in the foregoing embodiments, this invention was applied to a telephone system of the multi-channel access system utilizing a single control channel and a plurality of speech channels. However, it will be clear that the invention is also applicable to another type multi-channel system which utilizes only a plurality of speech channels and wherein a specific speech is made in the same manner as that utilizing the control channel.

Claims: Radio telephone system control apparatus comprising: a plurality of radio telephone sets (5, 5' ), each having a transceiver (8, 19, 8' , 19' ); a master apparatus (4) connected to a wired telephone channel; a master apparatus transceiver (14,16) in said master apparatus for exchanging radio telephone signals between the master apparatus and the radio telephone set transceiver (8, 19, 8' , 19' ); means (15) provided in said master apparatus for detecting a ring signal on said wired telephone channel; means (15, 18, 18') for sending a paging signal to the radio telephone set transceivers (8, 19, 8' , 19' ) from the master apparatus transceiver (14,16) when said ring signal is detected by said detecting means; means (405,410) provided in each of said radio telephone sets (5, 5' ) for receiving intermittently and at different time periods said paging signal means (9, 17, 9' , 17' ) provided in each of said plurality of radio telephone sets (5, 5' ) for sending a paging response signal to the master apparatus transceiver (14,16) from the radio telephone set transceivers, in response to reception of said paging signal during a respective time period; means responsive to said paging response signal for sending from the master apparatus transceiver to transceiver for each of the said radio telephone sets a channel designating signal; means for switching the radio channel of the master apparatus transceiver to a radio channel corresponding to said channel designating signal; means responsive to said channel designating signal for switching a radio channel of the transceiver of the radio telephone set which has received said paging signal to a radio channel corresponding to said channel designating signal, means responsive to said channel designating signal for switching a radio telephone set which has not received said paging signal to a wait state; thereby controlling the connection between said wired telephone channel and any one of said plurality of radio telephone sets (5,5') in response to the ring signal on said wired telephone channel by means of a single master apparatus (4). The radio telephone system control apparatus according to claim 1, characterised in that said means for sending said channel designating signal sends said channel designating signal to all of said radio telephone set transceivers (8, 19, 8', 19' ) and all said radio telephone set transceivers include means for switching the respective radio channels to a radio channel corresponding to said channel designating signal. The radio telephone system control apparatus according to claim 1, characterised by ; means for sending to the transceiver of the radio telephone set (5, 5' ) which has received said paging signal a bell ringing status signal from the master apparatus transceiver after the radio channel of the master apparatus transceiver (14,16) has been switched to a speech channel corresponding to said channel designating signal; means provided in said radio telephone set for producing a call tone in response to said bell ringing status signal; and means responsive to said call tone for sending an off-hook signal to said master apparatus transceiver (14,16) from the radio telephone set transceiver when said radio telephone set hooks off; thereby interconnecting said wired telephone channel and the radio telephone set which has sent out the off-hook signal. The radio telephone system control apparatus according to claim 3, characterised in that said bell ringing signal is sent to each of said radio telephone sets (5,5'). The radio telephone system control apparatus according to claim 1, characterised by : means (15,16) for sending to the radio telephone set transceiver of the radio telephone set (5,5') which has received said paging signal a bell ringing status signal from said master apparatus transceiver (14,16) when there is a ring signal on said wired telephone channel after the radio channel of the master apparatus transceiver (14,16) has been switched to a speech channel corresponding to said channel designating signal, and sending a bell not-ringing signal when there is no ring signal on said wired telephone channel; means provided in said radio telephone set (5, 5' ) for generating a call tone in response to said bell ringing signal; means responsive to said call tone for sending an off-hook signal to the master apparatus transceiver (14,16) from the radio telephone set transceiver (8, 19, 8', 19' ) when said radio telephone set (5, 5' ) hooks off; and means for returning the telephone system to a waiting state when no bell ringing status signal is received by said radio telephone set transceiver. The radio telephone system control apparatus according to claim 5, characterised by means for sending said bell ringing status signal to all of the radio telephone sets. The radio telephone system control apparatus according to claim 1, characterised by means for sending said paging signal and said channel designating signal over an interval longer than a period of intermittent reception. A radio telephone system control method of the type wherein a connection between a wired telephone channel and a plurality of radio telephone sets (5,5') is controlled by a single master apparatus (4) connected to said wired telephone channel, said method being characterised by comprising the steps of: detecting a ring signal on said wired telephone channel; sending a ringing signal to said plurality of radio telephone sets (5,5') from said master apparatus (4) when said paging is detected; sending a paging response signal to said master apparatus (4) from one of said plurality of radio telephone sets (5, 5' ) which has received said paging signal, said radio telephone sets (5,5') each receiving said paging signal intermittently and at different periods of time to one another; sending a channel designating signal to said plurality of radio telephone sets (5,5') from said master apparatus (4) in response to said paging response signal; switching a radio channel of said master apparatus (4) to a radio channel corresponding to said channel designating signal; switching a radio channel of the radio telephone set (5,5') which has received the paging signal to a radio channel corresponding to said channel designating signal in response to said channel designating signal; switching a radio telephone set (5,5') which has not received the paging signal to a wait state in response to the channel designating signal; and establishing a speech channel between the radio telephone set (5,5') which has received the paging signal and said wired telephone channel connected to said master apparatus (4). The radio telephone system control method according to claim 8, characterised by sending a bell ringing status signal from the master apparatus to the responding radio telephone set (5,5') after the radio channel of said master apparatus (4) has been switched to a speech channel corresponding to said channel designating signal; generating a call tone from one of said radio telephone sets in response to said bell ringing signal; sending an off-hook signal to said master apparatus (4) from said one of said radio telephone sets which has gone off-hook in response to said paging tone so as to interconnect said wired telephone channel and said radio telephone set which has sent out said off-hook signal. The radio telephone system control method according to claim 8, characterised by : sending a bell ringing status signal from said master apparatus (4) when a ring signal is detected on said wired telephone channel to said plurality of radio telephone sets (5,5') after the radio channel of said master apparatus (4) has been switched to a speech channel corresponding to said channel designating signal, and sending a bell not ringing signal when no ring signal is detected; generating a call tone in response to said bell ringing signal from said plurality of radio telephone sets; sending an off-hook signal to said master apparatus (4) from said plurality of radio telephone sets when one of said plurality of radio telephone set goes off-hook in response to said call tone; and restoring said radio telephone sets to a waiting state when said radio telephone sets do not receive said bell ringing status signal so as to interconnect said wired telephone channel and said radio telephone set which has sent out said off-hook signal.

Inventors: ITO KOICHI, MURATA YOSHITOSHI, YOSHIZAWA KAZUHIRO, YOTSUTANI AKIO, ITO, KOICHI, MURATA, YOSHITOSHI, YOSHIZAWA, KAZUHIRO, YOTSUTANI, AKIO
Applicants: NIPPON ELECTRIC CO, NIPPON TELEGRAPH & TELEPHONE, TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA, NEC CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Application year: 1986
Main classification: H04M1
IPC codes: H04M1