Cellular cordless telephone

~29;2~ CELLULAR CORDLESS TELEPHONE Background of the Invention The present invention is generally related to cellular telephones and more particularly to an improved cellular cordless telephone for providing both cellular and cordless telephone services.

In the prior art, cordless telephones typically are used in the home to allow the user to place and receive telephone calls~at any point throughout the house. Such cordless telephones are connected to the user's telephone landline. However, due to their limited range, such cordless telephones are not sui~able for use in vehicles.

Vehicular communications are typically achieved by means of radio telephone systems, the most prevalent being cellular telephone systems. A cellular telephone allows the user to place and receive telephone calls at any point throughout a large metropolitan area. However, the cost of a cellular telephone call is as much as seven times the cost of a cordless telephone call, since cordless telephone calls are made by way of the user's telephon2 landline and cost the same as landline telephone calls, while cellular telephone calls are made by~way o~ expensive cellular base stations and cellular swit¢hing equipment and cost much more than landline telephone calls.

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~ 35 ~F ~2~ - 2 - CE00058R Objects of the Invention Accordingly, it is an object of the present invention to provide an improved cellular cordless telephone that may place both cellular telephone calls and cordless telephone calls.

It is another object of the present invention to provide an improved cellular cordless telephone that automatically operates as a cordless telephone whenever it is in range of its corresponding cordless base station.

Brief Description of the Drawinqs Figure 1 is a block diagram of a cellular cordless telephone system embodying the pre ent invention.

Figure 2 is a block diagram of a cellular cordless telephone embodying the present invention.

Figure 3 is a block diagram of another embodiment of a cellular cordless telephone according to the present invention.

Figure 4 is a flow chart for the process used by the cellular cordless telephones in Figures 2 and 3 for placing and receiving cellular and cordless telephone calls.

Figure 5 is a flow chart for tha process used by the cellular cordless telephones in Figures 2 and 3 for originating a telephone call as a cellular telephone call or a cordless telephone call according to user selectable preference~ Figure 6 is a flow chart for the process used by the cellular cordless telephones in Figures 2 and 3 for receiving a telephone call as a cellular telephone call or a cordless telephone call according to user selectable preference.

~2~ ' Figure 7 is a flow chart for the process -used by the cellular cordless telephones in Figures 2 and 3 for simultaneously processing both a cellular telephone call and a cordless telephone call and three-way linking both calls.

Figure 8 is a flow chart for the process used by the cellular cordless telephones in Figures 2 and 3 ~or automatically transferring between a cellular telephone call and a cordless telephone call.

Figure 9 is a detail circui~ diagram for audio switch 150 in Figure 2.

Description of the Prefe~ed Embodiment In Figure 1, there is illustrated a block diagram of a cellular cordless telephone system embodying the present invention.

The system includes a telephone company phone system tTELCO) 184, connected by telephone landlines to a cordless base station 180 having a landline telephone number located in a home or office 181 and to a community cordless base station 188 having a telephone landline number in another office, building, or other geographical location.

Cordless base stations 180 and 188 communicate with the cellular cordless telephone (CCT) 10 through antennas 182 and 189.

Antennas 182 and 189 may be implemented as telescoping whip antennas.

Cordless base stations 18û and 188 may be any conventional cordless base station, such as, for example, the base station shown and described in Panasonic operating instructions, entitled "Cordlessphone Model No. KX-T3000 EASA-PHONE*", published by and available from the Panasonic Company, One Panasonic Way, Secaucus, New Jersey, 07094.

Additional community cordless base stations 188 may be~ located throughout a metropolitan area ior providing shared telephone service to CCI`s 10.

In this case, cordless base station 188 may include additional equipment for billing calls to the cellular telephone number of CCT 10.

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,~, : -, ~Z9~04~ Also connected through telephone landlines to the same or a different telephone company phone system (TELCO) 198 is the cellular control terminal 196 (see U.S. patent no. 4,268,722) with its associated cellular base station (s) 190 (see U.S. patent no. 4,485,486.

Cellular base station 190 incorporates both a receive antenna 192 and a transmit antenna 194 (see U.S. patent no. 4,369,520 for communicating with CCI's 10.

CCT 10 may be a mobile unit installed in a vehicle, a transportable unit which is a mobile unit and battery installed in a carrying case, or a hand-held portable unit. CCI 10 includes an antenna 118 for the cordless radio channels and an antenna 128 for the cellular radio channels as illustrated by the embodiment of CCI 200 in Figure 3, or may include a single antenna, is illustrated by the embodiment of CCI 100 in Figure 2.

In the U.S.A., the cordless radio channels are in the frequency band from 46 - 49 mHz and the cellular radio channels are in the frequency band from 824 - 894 mHz.

In Figure 2, there is illustrated a detailed block diagram of a first embodimentof a CCI 100 according to the present invention. CCIl 100 includes a cordless telephone transceiver 110, antenna 118, cellular telephone transceiver 120, antenna 128, microcomputer 130, keypad 140, display 180, audio switch 150, and handset 160 including speaker 162 and microphone 164.

Alternatively, as shown by dashed-lines in Figure 2, cordless telephone transceiver 110 and cellular telephone transceiver 120 may be coupled to a single antenna 119 in place of antennas 118 and 128 by way of low-pass filter 185 and high-pass filter 187, respectively.

Cordless telephone transceiver 110 may be any conventional cordless telephone transceiver, such as, for example the ~2~ transceiver shown and described in the aforementioned Panasonic operating instructions, entitled "Cordlessphone Model No. KX-T3000 EASA-PHONE".

Cellular telephone transceiver 120, microcomputer 130, keypad 140, and handset 160 likewise may be any commercially available cellular transceiver, such as, for example, the transceiver shown and described in Motorola instruction manual number 68P81049ES5, entitled "DYNATAC* Cellular Mobile Telephone", published by and available from Motorola C ,&E Parts, 1313 East Algonquin Road, Schaumburg, Illinois 60196.

Referring to Figure 9, audio-switch 150 may be imp]emented with two-to-one mu]tip]exing analog switches 151 - 155 which select between audio signa]s of audio circuitry 116 in cord]ess transceiver 110 and audio circuitry 126 in cellu]ar transceiver 120 under control of select signals SELECI 1, SELF.CT2 and LINK from microcomputer 130.

Select signal SELECI2 enables switches 151 and 152 when it has a binary one state, select signal SELECI 1 enables switches 153 and 154 when it has a binary one state, and se]ect signa] LINK enables switches 152, 154 and 155 when it has a binary one state.

Depending on which is enabled, analog switches 151 and 153 couple speaker 162 to receive audio from audio circuitry 116 and audio circuitry 126, respectively.

Similarly, depending on which is `enabled, analog switches 152 and 154 couple microphone 164 to transmit audio of audio circuitry 116 and audio c;rcuitry 126, respectively.

If three-way ]inking is selectedj analog switches 152 and 154 couple microphone 164 to transmit audio of both audio circuitry 116 and audio circuitry 126, and analog switch 155 coup]es speaker 162 to receive audio of both audio circultry 116 and audio circuitry 126 by way of summing amplifier 159.

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~Z~2~ - 6 - CE00058R Referring to CC~ 100 in Figure 2, microcomputer 130 is programmed in accordance with Figure~ 4-8 for operating as a cellular telephone, a cordless telephone, or a cellular cordless telephone. That is, according to the present invention, CCT 100 may simultaneously operate as a cellular telephone and a cordless telephone. When operating as a cellular telephone, control signals 131 TX ENABLE and 132 RX ENABLE of microcomputer 130 enable cellular transmitter 124 and cellular receiver 122, respectively. In addition to control signals 131 and 132 to cellular transceiver 120, microcomputer 130 also monitors control signals 133 R5SI, 134 RX DATA and 135 TX DATA for detecting signal strength, for detecting receive data and for sending transmit data, respectively, used in operation of cellular transceiver 120. When operating as a cordless telephone, control signal~ 141 and 146 of microcomputer 130 enable cordless receiver 112 and cordless transmitter 114, respectively. In addition to control signals 141 and 146 to cordless transceiver 110, microcomputer 130 also monitors control signals 142 SIGNAL QUALITY, 143 RING, 144 RX SECURITY CODE and 145 TX SECURITY CODE for detecting signal strength, ringing, and the receive security code, and for sending the transmit security code and dialed digits, respectively, used in operation of cordless transceiver 110. Dialed digits may also be encodad by keypad 140 as conventional multi-frequency tones which are coupled to transmit audio of cordless transceiver 110 by audio switch 150 during cordless operation.

Referring next to Figure 3, there is illustrated a block diagram of another embodiment of a cellular cordless talephone (CCT) 200 according to the present invention. CCT 200 includes a cordles~ telephone transceiver 210 in a se~arate housing with antenna 218 12~ 04~ - 7 - CE0005~R and connector 270, and a cellular telephone 220 in a separate housing with antenna 228 and connector 272.

Cordless telephone transceiver 210 may be a plug-in accessory which couples via connectors 270 and 272 to cellular telephone 220. When cordless telephone transceiver 210 is plugged into microcomputer 230 of cellular telephone 220, it operates in accordance with Figures 4-8. Cellular telephone 220 includes cellular transmitter 222, cellular receiver 224, microcomputer 230, keypad ~40, display 2~30, audio circuitry 226, audio switch 250 and handset 260 including speaker 26Z and microphone 264. Cordless telephone transceiver 210 may be any conventional cordless telephone transceiver, such as, for example the transceiver shown and described in the aforementioned Panasonic operating instructions, entitled "Cordlessphone Model No. KX-T3000 EASA-PHONE".

Cellular telephone 220 likewise may be any commercially available cellular transceiver, such as, for example, the transceiver shown and described in the aforementioned Motorola instruction manual number 68P81049E55, entitled "DYNATAC Cellular Mobile Telephone".

Micracomputer 230 of ce}lular telephone 220 is coupled to the cordless telephone transceiver 210 via the same control signals used in Figure 2. These control signals are TX/RX enable signals, signal quality signal, ring signal and TX/RX security code signals.

Audio circuitry 226 of cellular telephone 220 is coupled to audio switch 250 which can be implPmented with two-to-one multiplexing analog switches (see Figure 9) which select between audio signals from the cellular receiver 224 and transmitter 222 and cordless telephone receiver 214 and transmitter 212.

Re~erring now to Figure 4, there is illustrated a flow chart for the process used by the CCTs 100 and 200 in Figures 2 and 3, respectively, for placing and 1~92~ - 8 - CE00058R receiving cellular and cordless telephone calls.

Entering at block 302, the user activates the CCT. The microcomputer 130 and 230 monitors both the cellular and cordless systems for availability thereof and for incoming and outgoing calls. If the cellular system and/or cordless system are available, a corresponding availability indicator is enabled in display 180 and 280.

In cellular systems, the microcomputer scans pre-selected signalling channels to determine if cellular service is available. Next, at decision block 304, a check is made to determine if a call has been received. If not, N9 branch is taken to decision block 316 to determine if a call has been initiated by the user of the CCT. If not, N0 branch is taken back to block 304 to continue monitoring both the cellular and cordless systems for telephone calls.

Returning to decision block 304, if an incoming call has been received, YES branch is taken to decision block 306 where a check is made to determine if the incoming call is a cellular call. If so, YES branch is taken to block 308 where a cellular call indicator is activated or entered in display 180 and 280, and the incoming call is connected as a cellular call (e.g~, in Figure 2, cellular transceiver 120 is enabled by microcomputer 130). If the incoming call is not a cellular call, N0 branch is taken from block 306 to block 320 where a cordless call indicator is activated or entered in display 180 and 280, and the incoming call is connected as a cordless call (e.g., in Figure 2, cordless transceiver 110 is enabled by microcomputer 130).

Returning to decision block 316, if a call has been initiated by the user of the CCT, YES branch is taken to decision block 318 where a check is made to determine if the initiated call is a cellular call. If so, YES branch is taken to block 308 where the initiated call is ~2~ 4~ - 9 - CE00058R connected as a cellular call. If the initiated call is not a cellular call, N0 branch is taken from decision block 318 to block 320 where the initiated call is connected as a cordless call.

Referring now to Figure 5, there is illustrated a flow chart for the process used by the CCTs 100 and 200 in Figures 2 and 3, respectively, for originating a telephone call as ~ cellular telephone call or a cordless telephone call according to user selectable pre~erence.

Entering at block 400, the user activates the CrT.

Next, at block 402, a check is made to determine if a call has been originated by the CCT. If not, N0 branch is taken to wait for a call to be originated. If a call has been originated, YES branch is taken from decision block 402 to decision block 404, where a check is made to 1 determine if the user's preference is for cordless phone operation. If not, N0 branch is taken to block 406 to determine if a call can be placed on the cellular system.

If so, YES branch is taken to block 416 where the call origination is connected as a cellular call. If not, N0 branch is taken to decision block 408 to determine if a call can be successfully placed on the cordless system.

Referring back to decision block 4Q4, if preference is for cordless, YES branch is also taken to decision block 408. If a cordless call can be successfully placed, YES branch is taken from decision block 408 to decision block 414 where the call is connected as a cordless call. If not, N0 branch is taken to decision block 410 to determine if a call had been tried unsuccessfully on the cellular system. If so, YÆS branch is taken to block 402 to wait ~or a call origination. If not, N0 branch is taken to decision block 406 to determine if the call can be placed on the cellular system.

Referring now to FigurP 6, there is illustrated a flow chart for the process used by the CCTs 100 and 200 in Figures 2 and 3, respectively, for receiving a telephone call as a cellular telephone call or a cordless teIephone call according to user selectable preference.

~2~9~04~ - 10 Entering at block 500, the user activates the CCT.

Next, at decision block 502~ a check is made to determine if a call is being received by the CCI.

If not, NO branch is taken back to decision block 502.

If a call has been received, YES branch is taken from decision block 502 to decision block 504 to determine if the user's system preference matches the systern of the incoming call.

If so, YES branch is taken to decision block 508 to deterrnine if the call is on the cordless system.

If so, the YES branch is take to block 510 where the incoming call is connected as a cordless call.

If not, the NO branch is taken to block 512 where the incoming call is connected as a cellular ca]l.

Returning to declsion block 504, if the user's system preference does not match the system of the incorning call, NO branch is taken to decision block 506 to determine if the preference is for the cordless system.

If so, the YES branch is taken to decision block 514 to determine if the CCT is within range of the cordless base station (e.g., by sending the transmit security code and waiting for the receive security code from the cordless base station).

If not, the NO branch is taken to block 512 where the incoming call is connected as a cellular call.

If the cellular cordless telephone is within range of the cordless base station, YES branch is taken from decision block 514 to decision block 516 to deterrnine if the cellular systern will forward the unanswered incoming call to the landline of the cordless base station when the cellular phone cannot be reached.

This type of service is generally referred to as "call forwarding" (a process which redirects a call from the dialed cellular telephone number of ccr lo to the landline telephone number of cordless base station 180) and can be determined by polling stored information in the memory associated wi~h the CCI` microcornputer.

If not, NO brancb is taken to block 512 where the incoming call is conneGted as a cellular call.

If the cellular system will fo~ward the unanswered incoming call, YES branch is , :: :

,~, 12~;~0~1 ~ CE00058R taken from decision block 516 to block 518 where the cellular page from the cellular base station is ignored and thereafter to decision block 502 to wait for the incoming call to be received as a cordless call.

Returning to decision block 506, if the preference is for a cellular call, N0 branch is taken to decision block 520 to determine if the CCT is within range of the cellular base stations (does it have cellular service).

This is typically determined by scanning and selecting the strongest signalling channel ~rom the surrounding cellular base stations. If not, NO branch i8 taken to block 510, where the incoming call is connected as a cordless call. If the CCT is within range of the cellular base stations, YES branch is taken from decision block 520 to decision block 522 to determine if the landline system will forward the unanswered incoming call to the cellular system. This type of service is generally referred to as "call forwarding" and can be determined by polling stored information in the memory associated with the CCT microcomputer. If not, NO branch i8 taken to block 510 where the incoming call is connected as a cordless call. If the landline telephone system will forward the unanswered incoming call, YES branch is taken from decision block 522 to blsck 524 where the cordless page from the cordless base station is ignored and thereafter back to decision block 502 to wait ~or the incoming call to be received as a cellular call.

Referring now to Figure 7, there is illu~trated a flow chart for the process used by the CCTs 100 and 200 in Flgures 2 and 3, respectively, for simultaneously processing both a cellular telaphone call and a cordless telephone call and, if desired, three-way linking both calls.

Entering at block 600, the user activates the CCT.

Next, at block 602, one call is assumed to be in process - 12 - CE0005BR on either the cellular system or cordless system.

Proceeding from block 602 to decision block 604, a check is made to determine if a call has been received on th opposite system from ~he call in process. If so, YES branch is taken to decision block 608 to determine if the user has selected the dual-mode feature (e.g., by entering a predetermined code from the keypad). If not, N0 branch is taken back to decision block 604 and the current call remains in process. If the user has selected the dual-mode feature, YES branch is taken from decision block 608 to block 610 which alPrts the user of an incoming call on the alternat~ system. This type of service is generally referred to as "call waiting".

Next, at decision block 612, a ch~ck is made to see if the user acknowledges the second call. If not, NO branch is taken back to decision block 604 and the current call remains in process. If the user acknowledges the second call (e.g., by flashing the hookswitch), YES branch is taken from decision block 612 to decision block 614 to determine if the user has selected three-way linking (e.g., by entering a predetermined code from the keypad).

If so, YES branch is taken to block 616 which enables three-way linking of the user and the two calls, each of which is on a different system. Three-way linking may be accomplished by switchably coupling the combined receive audio signals from summing amplifier 159 via analog gate 155 to the speaker, and enabling both transmit audio switches 152 and 154 in Figure 3. If the user has not salected three-way linking, NO branch is taken from decision block 614 to block 618 to process both calls simultaneously, one over each system, but selection between them is made by the user so that only one party is in conversation with the user at a time. Selection between the calls may be made pressing a pre-selected key or set of keys on the Xeypad.

12~ - 13 - CE000~8R Returning to decision block 604, if a call has not been received on the opposite system, NO branch is taken to decision block 606 to determine if a call has been originated on the opposite system. If not, NO branch is taken back to decision block 604. If a call has been originated on the opposite system, YES branch is taken from decision block 606 to decision block 614 to determine if the user wants three~way linking, as described hereinabove.

Referring now to Figure 8, there is illustrated a flow chart for the process used by the CCTs 100 and 200 in Figures 2 and 3, respectively, for automatically transfering between a cellular telephone call and a cordless telephone call.

Entering at block 700, the user activates the CCT.

Next at ~lock 702, a call is assumed to be in process on one of the two systems. Proceeding from block 702 to decision block 704, a check is made to determine if the call in process is on the cordless system. If so, YES branch is taken to decision block 708 to determine if the CCT is still within range of the cordless base stations (e.g., signal quality is good). If so, YES branch is taken back to decision block 704. If the cellular cordless telephone is out of range of the cordless base stations, NO branch is taken from decision block 708 to decision block 710 to determine if the user has selected *ransfer of the cordless call to the cellular system (e.g., by entering a predetermined code from the keypad).

If so, YES branch is taken to block 714 where an attempt is made to transfer the cordless call to the cellular system. Assuming the called party has "call waiting", the ~ransfer is attempted by placing another call on the celIular system and waiting ~or the called party to answer. Thereafter, the path returns to decision block 704. If the user has not selected call transfer, NO ~2~ - 14 - CE00053R branch is taken from decision block 710 to block 712 where the cordless call is maintained as long as possible.

Returning to decision block 704, if the call is not on the cordless system, NO branch is taken to decision block 706 to determine if the CCT is still within range o~ the cellular base stations (e.g., signal quality is good). If so, YES branch is taken back to decision block 704. If the CCT is out o~ range of the cellular base stations, NO branch is taken from decision block 706 to decision block 716 to determine if the user has selected transfer of the cellular call to the cordless system (e.g., by entering a predetermined code ~rom the keypad).

If not, N0 branch is taken to block 720 where the cellular call is maintained as long as possible. If the user has selected call transfer, ~ES branch is taken from decision block 716 to block 718 where an attempt is made to transfer the cellular call to the cordless sy~tem.

Assuming the called party has "call waiting", the transfer is attempted by placing another call on the cordless system and waiting for the called party to answer. Thereafter, the path returns to decision block 704.

In summary, a unique cellular cordless telephone has been described that may be advantageously utilized for making both cellular telephone calls and cordless telephone call~. Whenever the cellular cordless telephone is within range of the cordless base station, telephone calls are preferably originated on the cordless system, or if currently in process, are transferred to tbe~cordless telephone system.