Patent Publication Number: US-2005143017-A1

Title: Docking station for enabling landline telephones to send/receive calls via a docked walkie-talkie-type mobile telephone

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      The present application claims benefit of U.S. Provisional Application No. 60/533,527 filed Dec. 31, 2003, and U.S. Provisional Application No. 60/623,189 filed Oct. 30, 2004. The entire disclosures of each of these provisional applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally to a docking station for a mobile telephone, and more specifically to a docking station that provides an interface to enable landline telephones to send and receive calls via a mobile telephone docked in the docking station, and to enable the landline telephones to utilize facilities and features provided by the mobile telephone via the docking station.  
      2. Related Art  
      In recent years, there has been an increasing desire among many in the general public to “keep in touch” or be available to others using telephony devices such as a home telephone, a mobile (wireless) telephone (also known as a cellular telephone or a cell phone), an office telephone, an office fax, etc. Each of these telephonic devices has a unique identification on the public telephone network: an individual telephone number. Thus, an individual must give out several telephone numbers in order to be reachable by others through various different telephonic devices.  
      The popularity of mobile telephones has led a growing number of mobile telephone users to abandon traditional landline telephones as their main home telephones in favor of using their mobile telephones as their main home telephones. Mobile telephones as home telephones provide the advantage of having only one telephone number for travel or home. Mobile telephones as home telephones, however, have several disadvantages in the current art. Generally, a mobile telephone cannot have extension telephones, which have the same telephone number as the mobile telephone and which are able to participate on the same telephone call. Further, many features that are available to a wired or landline telephone system are not available to a mobile telephone.  
      Additionally, it is often desirable to be able to communicate from one room to another in a premises. For example, communication is difficult between different levels in a house or among offices in a small office building. In such situations it is necessary to buy and install special intercom systems, a PBX (private branch exchange), or a key telephone system. However, none of these solutions is cost-effective or easily moved from one location to another.  
     SUMMARY OF INVENTION  
      The present invention relates generally to a docking station for a mobile telephone, in which the docking station provides an interface to enable landline telephones to send and receive calls via a mobile telephone docked in the docking station, and to enable the landline telephones to utilize facilities and features provided by the mobile telephone via the docking station. According to the invention, the docking station connects with the mobile telephone via the mobile telephone&#39;s multi-pin connector. The docking station determines the make and the model of the mobile telephone, i.e., the type of the mobile telephone, based on the multi-pin connector. Once the type is determined, the docking station utilizes its internal software/firmware to control the functions of the mobile telephone, by sending appropriate signals to the mobile telephone through the pins of the multi-pin connector.  
      According to an aspect of the present invention, the docking station determines which pins of the multi-pin connector correspond to power pins of the docked mobile telephone, and also determines an interface protocol for the docked mobile telephone. The docking station provides charging power to the mobile telephone as a regular charge, a trickle charge, or another type of charge, as required by the docked mobile telephone, in order to power the mobile telephone and to charge the internal battery of the mobile telephone, simultaneously.  
      According to another aspect of the invention, the mobile telephone may wirelessly “connect” to the docking station using a wireless protocol, such as Bluetooth®, Zigbee™ and wi-fi, for example. Signals such as voice signals and data signals are encoded/decoded into the wireless protocol by the docking station. In this manner, the mobile telephone does not have to be physically connected to the docking station while it provides its features to the landline telephones connected to the docking station.  
      According to yet another aspect of the present invention, the docking station controls the functionality of the mobile telephone via the connection pins to perform most or all of the functions of the mobile telephone responsive to telephone signals of telephones connected to the landline system. The docking station further includes circuitry to provide dial tone and dual-tone multi-frequency (DTMF) detection, to provide battery power, etc., to any analog telephone on the landline connected to the docking station. In this manner, any analog telephone connected to the landline may use the mobile telephone to make telephone calls via the mobile telephone. Further, any analog telephone connected to the landline wiring may be used to receive telephone calls via the mobile telephone. Advantageously, an echo canceller is incorporated in the docking station and is connected between the docking station and the analog telephone(s) in order to compensate for (cancel) an impedance imbalance, which can cause undesirable noise in the signal path.  
      According to a further aspect of the present invention, the docking station includes circuitry to receive data from the mobile telephone and circuitry to provide data-encoded signals to an analog line. For example, when the mobile telephone receives a Caller ID, the docking station converts a digital signal corresponding to the Caller ID into an analog frequency-shift-key (FSK) signal. This allows most currently available Caller-ID-enabled telephones and Caller ID boxes to receive and display a Caller ID. Other data-encoded signals received by the mobile telephone, such as short message service (SMS) signals and message waiting signals, for example, also may be similarly displayed.  
      According to yet another aspect of the present invention, the docking station determines which pair of two pairs of telephone wires are available to the docking station. When the docking station is plugged in to a telephone landline connector, the docking station tests a first pair of wires for an operative voltage from a central office. The docking station also tests a second pair of wires for an operative voltage. Then docking station selects a pair of wires that does not have a voltage present. Advantageously, the docking station provides an indication as to which pair of wires it is connected to and/or which pair or pairs of wires have a central-office voltage present.  
      Optionally, the testing of the pairs of telephone wires may be done manually via a selection switch on the docking station, which allows a user to manually select which of the pairs of wires to be tested. An indicator on the docking station indicates whether voltage is present on the pair of wires being tested.  
      According to still another aspect of the present invention, the docking station provides a voice and data intercom system between and among telephones connected to the landline of the premises. Any telephone on the landline may send a DTMF signal or string of signals to the docking station, which alerts the docking station that an intercom call is desired. The intercom number of the desired telephone (called telephone) is entered. A DTMF detector on the called telephone listens for its own intercom number, and rings if it detects its own intercom number. Advantageously, data messages, light signals, differential ringing tones, etc. may be delivered to a specific telephone.  
      According to a further aspect of the present invention, the docking station&#39;s software/firmware is updatable by connecting the docking station to a personal computer (PC). The PC is connected to a data network (e.g., the Internet) and downloads updates. The downloaded updates are formatted and loaded into the docking station by the PC. In this manner, new types of mobile telephones and other devices may be detected and controlled by the docking station without having to replace the docking station.  
      According to a still further aspect of the present invention, when the mobile telephone docked in the docking station is a “walkie-talkie”-type mobile telephone, also known as a “push-to-talk” or PTT-enabled mobile telephone, landline telephones connected to the docking station are able to function as “walkie-talkie”-type telephones. The docking station&#39;s software/firmware interprets signals from a predefined button or a hook switch on the landline telephone to correspond to the stop/start of speech. That is, signals from pressing and releasing the predefined button or from toggling the hook switch are interpreted to correspond to signals from a PTT button of a PTT-enabled mobile telephone. However, the predefined button or the hook switch need not be held down while a user is speaking. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be more readily understood from the detailed description of the preferred embodiment(s) presented below considered in conjunction with the attached drawings, of which:  
       FIG. 1  is a block diagram of a premises in which a docking station controls landline (wired) telephones, in accordance with an embodiment of the present invention;  
       FIG. 2  is a block diagram of the docking station of  FIG. 1 ;  
       FIG. 3  is a flow chart of an operation for detecting a mobile telephone docked to a docking station, according to an embodiment of the present invention;  
       FIG. 4  schematically shows a programming cable, according to an embodiment of the present invention;  
       FIG. 5  schematically shows a memory of a processor of a docking station, according to an embodiment of the present invention;  
       FIG. 6  is a flow chart of an updating operation of a processor of a docking station, according to an embodiment of the present invention;  
       FIG. 7  schematically shows components involved in the programming of a processor of a docking station, according to an embodiment of the present invention;  
       FIG. 8  schematically shows a configuration of a Bluetooth® adaptor device, according to an embodiment of the present invention;  
       FIG. 9  schematically shows a line-pair switch;  
       FIG. 10  is a flow chart of an operation for determining whether a telephone line is available for use by a docking station, according to an embodiment of the present invention;  
       FIG. 11  is a flow chart of an operation of a docking station to provide an intercom function, according to an embodiment of the present invention;  
       FIG. 12  is a block diagram of components involved in an intercom function of a docking station, according to an embodiment of the present invention;  
       FIG. 13  is a block diagram of an intercom station, according to an embodiment of the present invention;  
       FIG. 14  is a block diagram of a paging/intercom station, according to an embodiment of the present invention; and  
       FIGS. 15A and 15B  are flow charts showing operation sequences for when a landline telephone is used to send/receive calls through a PTT mobile telephone via a docking station, according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Turning now to  FIG. 1 , a block diagram of a wire-line premises is shown, generally at  100 . The premises  100  includes a telephone company interface (herein “telco interface”)  102 . According to the prior art, the telco interface  102  connects the premises  100  to a public switched telephone network (PSTN)  104  via a four-wire telephone line  106 . The telco interface  102  connects one or more analog telephone instruments, represented by telephones  110 ,  112 , and  114  to each other and to the telephone line  106  via four-wire lines  116 ,  118 , and  120 , respectively. As is known in the art, each telephone  110 ,  112 , and  114  receives power from the PSTN  104  in order to provide basic telephonic service. Additionally, any of telephones  110 ,  112 , and  114  may have a supplementary power supply to implement features such as Caller ID, message-waiting lights, etc. Furthermore, each of telephone  110 ,  112  and  114  is dual-line capable, as is known in the art.  
      Further, a wireless telephone  130  is in communication  132  with a cell site  134 . The cell site  134  is part of a wireless network  136 . The wireless network  136  provides communication and other functionality to a wireless telephone  130 , as is known in the art. The wireless network  136  is connected to, or is a part of, the PSTN  104 , also as is known in the art.  
      A wireless telephone docking station  150  in accordance with an exemplary embodiment of this invention also is connected to the telco interface  102  via a four-wire line  152 . The docking station  150  also connects to the wireless telephone  130  via a connector (not shown, but well known in the art) appropriate for the manufacturer or type of the wireless telephone  130 . In this manner, the docking station  150  is connected to all of the telephone lines  116 ,  118 , and  120  as well as the wireless telephone  130  via the telco interface  120 .  
      According to this exemplary embodiment of the present invention, the docking station  150  senses the presence of the wireless telephone  130 . The docking station  150  then determines whether there is a pair of wires available to which it may connect. The docking station  150  measures a voltage on a first pair of wires. If a line voltage (e.g., 48 V) is present, then the first pair of wires is connected to the PSTN  104 . A second pair of wires then is tested. If there is no line voltage, the docking station  150  supplies a line voltage to activate the second pair of wires to each of telephone  110 ,  112 , and  114 .  
      Optionally, testing of the pairs of telephone wires may be done manually via a selection switch (not shown) on the docking station  150 , which allows a user to manually select which of the pairs of wires to be tested. An indicator (not shown) on the docking station  150  indicates whether voltage is present on the pair of wires being tested. For example, the indicator may be an LED device with red and green LEDs, such that, when the red LED lights up it indicates that there is voltage present; and when the green LED lights up it indicates that no voltage is present. Similarly, the indicator may be an audible device such that a first type of audible sound is heard when there is voltage present, and either silence or second type of audible sound is heard when no voltage is present.  
      Once the docking station  150  is connected to the telephones  110 ,  112 , and  114 , then any of the telephones  110 ,  112 , or  114  may use the wireless telephone  130  as if it was a landline telephone. The telephones  110 ,  112 , and  114  may make outgoing telephone calls, receive incoming calls, receive Caller IDs, receive short-message-service (SMS) messages, etc. Such functionality is provided by the docking station  150  in conjunction with the wireless telephone  130 .  
      Turning now to  FIG. 2 , a block diagram of the docking station  150  is shown. A line-pair switch  202  is shown in this exemplary embodiment. The line-pair switch  202  is a mechanical double-pole, double-throw (DPDT) side-actuated slide switch. The line-pair switch  202  allows a user to manually select connection of the docking station  150  to either Line 1 or Line 2 (an inner or an outer pair of conductors on a telephony jack). Alternatively, the line-pair switch  202  may be an automatic switch that senses a voltage on the telephone lines and connects to a pair of wires with no voltage.  
      The line-pair switch  202  is connected to line-filtering circuitry  204  comprised of two pi-filters that attenuate unwanted out-of-band signals. A fuse in the line-filtering circuitry  204  protects the docking station  150  from high-current differential surges. The line-filtering circuitry  204  also is comprised of, in this exemplary embodiment, a diode-bridge crowbar-sideactor clamp to protect a subscriber-line interface circuit  206 .  
      The subscriber-line interface circuit (SLIC)  206  is comprised of, in this exemplary embodiment, a Si3210 IC, available from Silicon Labs. The SLIC  206  is described in detail in a Si3210KT datasheet, which is incorporated by reference herein in its entirety. In general, the SLIC  206  performs the following functions: 
          tip/ring battery voltage,     ring generation,     FSK and CAS detection,     signal generation,     DTMF detection,     analog and digital audio programmable gain,     envelop detection,     varilosers, and     Watchdog functionality.        

      Relatively few discrete components are required for the Si3210 DC-DC converter to generate a negative DC battery voltage level (+/−48VDC) required to operate analog telephone functions.  
      The docking station  150  also includes a processor  208 . In this exemplary embodiment, the processor  208  is comprised of a 16 bit microcontroller with 128 K bytes of ROM and 10 K bytes of RAM. A main clock source is a 9.216 MHz, 3.3V, 100 PPM crystal. The processor  208  is responsible for controlling all timing and functionality of the docking station  150 .  
      A key scan circuit  210  and a keyboard (not shown, but well known in the art) consisting of two rows and one column is connected to the processor  208 . The keyboard is checked every 16 ms to determine whether a key has been pressed. If a key matrix closure is detected by the key scan  210 , a key scan algorithm is executed to determine the exact key pressed. A key must be pressed for two consecutive scans (32 ms) in order to be valid.  
      A status LED  212  also is connected to the processor  208 . The status LED  212  is a low-cost dual-color (e.g., green/red), T-1¾, three-leaded diffused LED. The status LED  212  is responsible for indicating one of three states of the docking station  150  to a user: 
          Solid GREEN Indicator: the docking station  150  is connected to the wireless telephone  130  (via a cable or wireless protocol);     Flashing GREEN Indicator: the docking station  150  is powered on but is not connected to the wireless telephone  130 ; and     Solid RED Indicator: indicates that: 
            1. The docking station  150  is plugged into a telephone line that is already in use by a landline service. This is an error indicator and the user should disconnect the landline service before plugging in the docking station  150 ; and/or     2. Power to the docking station  150  is insufficient.    
               

      A power supply  214  provides AC-DC power from a transformer that converts 120VAC to 9VDC RMS, depending on a load drawn by the docking station  150 . Noise at an input rail for 9VDC is reduced by filtering capacitors. A zener diode clamp is used to protect a regulator. The 9VDC input rail feeds three separate supplies: VDC, Regulated +3.3VDC, and Charge. The VDC is the reference voltage rail required for a Si3210 SLIC DC-DC converter to generate+/−48VDC line voltage. The Regulated +3.3VDC is a regulated supply source for almost all integrated circuits (ICs) in the docking station  150 .  
      The power supply  214  also is connected to a charger interface  216 . The 9VDC input is dropped across a high-current diode and supplies charging circuitry in the charger interface  216 . This section supplies power for the charging circuitry and current required for trickle charging a connected wireless-telephone battery. Transistors, a high-current amplifier, a current control 3 W resistor, noise reduction capacitors, and voltage-level setting components all work to form an output of a trickle charger. The charger interface  216  also is connected to a processor output to turn the charging circuitry off. If a CHG_OFF output is high, the charger interface  216  is disabled. The high-current amplifier is used to provide charger voltage feedback via a processor A/D input.  
      A cell phone interface  218  is connected to the charger interface  216 . The cell phone interface  218  is comprised of a detection circuits for detecting a PCMCIA connector, a cable, and a cell phone (wireless telephone). The charging circuitry charges a battery of the wireless telephone  130  at a voltage and a current appropriate for the type of the wireless telephone  130  connected to the docking station  150 . Optionally, the charging circuitry provides a charge to the wireless telephone  130  in an amount ranging from a full charge to a medium charge to a trickle charge. Optionally, the docking station  150  includes an visual indicator for showing a charging status of the battery of the wireless telephone  130 .  
      The PCMCIA connector is a 15-pin male, surface-mount PCB connector with a locking key. It is the primary interface for the docking station  150  and a cell phone cable assembly or a wireless module. For example, the PCMCIA connector is configured to connect with any of a plurality of wireless modules such as, for example, Bluetooth® dongle, a wi-fi module, and a Zigbee™ module. Signals assigned to each pin on the PCMCIA connector are unique to the docking station  150  but are universal for an entire family of cell-phone station products.  
      Optionally, the docking station  150  includes one or more internal circuits for providing wireless connectivity to a mobile telephone via, for example, Bluetooth®. wi-fi, and/or Zigbee™ standards.  
      A detection circuit for detecting a cable or an accessory consists of capacitors, resistors, and a buffering amplifier. A resistor forms half of a divider once the cable assembly (or the wireless module) is plugged into the docking station  150 . Depending on the resistor in the cable assembly, an output of the divider is routed to the processor  208  to determine which type of cable is connected and thus to determine which type (e.g., manufacturer and model) of cellular telephone is connected.  
      A wireless-telephone detection circuit includes a comparator circuit. An LMV331DBV Comparator IC is used to compare a received serial-data input (RX) to a DC voltage level set by discrete components. If there is no wireless telephone connected, the RX will be low and the output of the comparator will also be low (&lt;0.5VDC). If there is a wireless telephone connected, the RX will be at a level greater than 1.03V and thus the output of the comparator will be high (&gt;2.4Vdc). The output of the comparator then is routed to the processor  208 . When no cable or cell phone is connected, a pull-down resistor at an input of the comparator ensures that the comparator is not falsely triggered by transient noise.  
      An audio section  220  is connected to both the cell phone interface  218  and the processor  208 . The audio section  220  is comprised of an analog RX and TX (reception and transmission) gain and filtering circuitry unit  222 , a codec  224 , and an echo canceller  226 .  
      The analog RX and TX gain and filtering circuitry unit  222  comprises single-ended and differential rail-rail amplifiers, capacitors, and resistors used for buffering and adjusting analog gains between a wireless-telephone output and an input of the codec  224 . The analog RX and TX gain and filtering circuitry unit  222  also filters unwanted out-of-band signals.  
      According to this exemplary embodiment of the present invention, the codec  224  is a Motorola MC145483. The MC145483 is a 3V, 13 Bit, Linear PCM codec. A Frame Sync (Bit_FS) is set at 8 KHz and a codec clock is set at 256 KHz. As is known in the art, the codec  224  performs the following functions: digitizing and reconstructing human voice, and high- and low-Pass filtering.  
      The echo canceller  226  comprises, in this exemplary embodiment, a Zarlink MT93L16AQ Echo Canceller IC. The echo canceller  226  contains both an acoustic and a line echo canceller. It is designed to be powered by a single 2.7-3.3V DC supply but has 5V tolerant inputs. The MT96L16AQ performs the following functions: 
          digital audio gain control,     track changing echo environment with fast convergence times,     0 dB acoustic echo return loss (ERL) and 0 dB line echo return loss,     adaptation algorithm to allow for convergence even during double talk,     full duplex speech with no switched loss on audio paths,     auto gain control (AGC) on speech paths,     offset nulling of all 2 PCM channels,     howling prevention, and     mute options on speech paths.        

      Turning now to  FIG. 3 , processing when a connection is made at cell phone and cable interface  218  according to an exemplary embodiment of this invention is shown. Processing starts at step  300  and proceeds to step  302 , where a determination is made as to whether a cable is sensed. In this exemplary embodiment, when a wireless telephone or a programming cable (such as the programming cable  402  of  FIG. 4 ) is plugged into the cell phone and cable interface  218  of the docking station  150 , a cable connection is sensed by detecting a wire of the cable. The wire has a resistance (R) which may be 0 ohms or greater. The wire is connected to an A/D converter (not shown, but well known in the art) at the cell phone and cable interface  218 . If no cable is detected at step  302 , then processing loops back to step  300 .  
      If a cable is detected at step  302  then processing proceeds to step  304 . At step  304 , the processor  208  compares an A/D reading to a look-up table stored in a program memory. An exemplary memory layout  500 , including a look-up table  502 , is illustrated in  FIG. 5 .  
      Processing continues to step  306 , where a wireless telephone “family” grouping for the cable is determined. In accordance with the exemplary embodiment of the present invention, a “family” may be a manufacturer&#39;s grouping (e.g., Motorola v-series), a specific phone (e.g., Kyocera Smartphone) or a manufacturer (e.g., Nokia). The A/D reading also may be used to differentiate between types of devices (i.e., Bluetooth® module, accessory, programming cable, cell phone, etc.).  
      If, at step  306 , a family type cannot be determined, a default is loaded at step  308 . If a family is determined, then processing proceeds to step  310 , where protocol parameters for the family are loaded. Processing from both step  308  and step  310  moves to step  312 .  
      At step  312 , a determination is made as to whether the connected device responds to a family protocol. Using the family&#39;s type as an index, the docking station  150  tests all protocols associated with that family and waits for a response from the connected device. That is, the docking station  150  attempts to communicate via an AT type command set or any number of proprietary protocols (i.e., one-wire systems, UARTs with specially encoded data words, etc.). This test requires hardware with sufficient flexibility to accommodate this under software control.  
      If no satisfactory response is obtained, then processing loops back to the start at step  300 . If, at step  312 , a satisfactory response is obtained, processing moves to step  314 . At step  314 , a determination is made as to whether the connected device is a known model. The processor  208  compares a type of communication protocol to a model lookup table  504  ( FIG. 5 ) for identification.  
      If, at step  314 , an exact model is not identified, the charger interface  216  is disabled at step  316  and default audio, echo canceling, and command control parameters are set at step  318 . If the exact model is identified at step  314 , then, at step  320 , the hardware is configured as shown in the model lookup table  504 .  
      As described above, the echo canceller  226  is included in the audio section  220  in accordance with the exemplary embodiment of the present invention. Some telephone devices present audio with side tone removed, and some do not. Likewise, some telephone devices have echo cancellers on board and pass audio through to their accessory interface with echo canceling enabled, and some do not. The echo canceller  226  allows the docking station  150  to be able to adapt to different environments “on the fly” or as necessary.  
      The charger interface  216  also is set up when a wireless telephone is detected. Each wireless telephone generally has a unique charging signature. The charger interface  216  and the processor  208  alter voltage, current, and on/off cycle times depending on the wireless telephone&#39;s requirements. The audio section  220  also is customized based on the model of the connected wireless telephone. The TX/RX side tone paths are adjusted (at  222 ) based on known parameters of the connected wireless telephone.  
      If, at step  324 , the processor  208  determines that a programming cable is connected to the cell phone and cable interface  218 , the docking station  150  assumes a programming mode at step  322 . In accordance with this embodiment of the present invention, a UART is used for programming (not shown, but well known in the art). Processing moves through connector A to  FIG. 6 . If a programming cable is not detected at step  324 , then processing ends at step  326 .  
      Turning now to  FIG. 6 , a flowchart of a programming operation of the processor  208  of the docking station  150  is shown. When the programming mode is entered, the docking station  150  awaits instructions. Typically, as illustrated by an arrangement  700  shown in  FIG. 7 , the docking station  150  is connected to a PC  702  for programming. A connection  704  may be via serial port, a USB port, or other means, such as a wireless connection. A software program resides on the PC  702  (or on a special programming device). New programs may be obtained from a source  706 , such as a disk or a Web site. New programs may be downloaded via the Internet, represented by a line  708  in  FIG. 7 .  
      The memory layout schematically shown in  FIG. 5  allows the entire memory of the docking station  150  to be updated or, alternatively, portions of the software stored in the memory may be selectively updated. Returning to  FIG. 6 , at step  602  a determination is made as to whether all of the memory is to be programmed. If it is, then processing proceeds to step  604  where the memory of  FIG. 5  is erased, reprogrammed, and verified. Processing continues to step  606 , where the processor  218  is reset.  
      If, at step  602 , a determination is made that not all of the memory is to be updated, processing moves to step  608 . At step  608 , a determination is made as to whether a new driver is to be added. If a new driver is to be added, then the new driver is programmed at step  610  and the driver lookup table  508  and the drivers library  506  are updated and verified at step  612 . Processing ends in reset oval  606 .  
      If, at step  608 , a new driver is not to be added, then processing proceeds to step  614 . At step  614 , a determination is made as to whether a driver is to be updated. If a driver is to be updated, then processing proceeds to step  616 , where the old driver is erased from the drivers library  506  ( FIG. 5 ). Processing continues to step  618 , where the new driver is programmed and the drivers library  506  and the driver lookup table  508  are updated and verified. Processing ends in reset oval  606 .  
      If, at step  614 , a driver is not to be replaced, then processing proceeds to step  620 , where a determination is made to exit program mode. If a determination is made to exit the programming mode, then the processor  218  resets at step  606 . Otherwise, processing loops back to step  602 .  
      Turning now to  FIG. 8 , a further embodiment illustrates an ability to update the docking station  150  through a Bluetooth® module  802 . Essentially, the Bluetooth® module  802  wirelessly communicates with the PC  702  ( FIG. 7 ) and acts as if it was the programming cable  704  ( FIG. 7 ).  
      In general, the Bluetooth® module  802  appears as a device to the processor  208  ( FIG. 2 ) because essentially it looks like a wireless telephone with its own set of unique family and model parameters. The Bluetooth® module  802  is connected to the codec  224  and then to the analog RX and TX gain and filtering  222 . The Bluetooth® module  802  also is connected to the processor  208  for data RX and TX and to the cable and cell phone interface  218 .  
      Turning now to  FIGS. 9 and 10 , the line-pair switch  202  ( FIG. 2 ) and an algorithm for operation thereof, respectively, are shown. There is an inherent problem with connecting the docking station  150  to existing home or landline telephone wiring. Typical landline services are not allowed to interface with new devices that supply line current. In response, the docking station  150  detects whether a line pair is already in use by a landline (that is, connected to a central office or other device supplying battery voltage). The docking station  150  senses a combination of a line voltage and current to determine (and indicate to the user) whether a line pair is already in service.  
      In  FIG. 9 , a switch  902  tests both line pairs  904  (LP 1 ) and  906  (LP 2 ) for presence of a landline voltage, current, or both, either manually or under software control. The switch  902  is polarity insensitive, as battery feeds can be positive or negative. Testing of the lines is according to the flow chart of  FIG. 10 .  
      Processing starts at step  1002  where a reset has occurred, whether manually, on power up, or by software control (see  FIG. 6 ). A determination is made at step  1004  as to whether a PSTN voltage is detected. If it is, then processing proceeds to step  1006  where an alarm is set. The alarm may be a light, an audible alert, or both. If a landline is detected, the docking station  150  is disabled until the situation is corrected. Processing continues to step  1008 , where a determination is made as to whether a timer has expired. If the timer has expired, processing returns to step  1003 .  
      If, at step  1008 , the timer has not expired, a determination is made at step  1010  as to whether an off-hook current is detected. If an off-hook current is detected, then processing loops back to step  1004 . This test is made in case a landline is plugged in or connected to the PSTN  104  after the docking station  150  is connected to a line. If an off-hook current is not detected, then the docking station  150  is enabled for docking, and processing ends at step  1012 .  
      Turning now to  FIG. 11 , a generic call flow is shown, which describes an aspect of the present invention, wherein the docking station  150  provides telephone-to-telephone (intercom) service. While this aspect of this invention is described in terms of a voice intercom, other uses, such as message signaling and signal lighting, will be apparent to one skilled in the art after studying this specification.  
      At line  1100 , the docking station  150  is providing battery and line supervision to the telephones  110 ,  112 , and  114 . At line  1102 , the docking station  150  detects that a telephone, the telephone  112  in this example, is off hook (i.e., current is flowing, as is known in the art). At line  1104 , the docking station  150  delivers a dial tone. At line  1106 , the user of the telephone  112  sends a predetermined intercom code to the docking station  150 . The code may be any string of DTMF digits or symbols (i.e., “*”).  
      Next, the docking station  150  recognizes the DTMF signal, turns off the dial tone and waits for further digits. At line  1108 , the user of the telephone  112  enters an extension code for the telephone  114 . At line  1110 , the docking station  150  translates the extension code and sends an alerting signal. The alerting signal may simply be a ringing signal on all extensions or a differential ringing signal. If the telephone  114  is equipped with its own power supply and processor, the docking station  150  sends a predetermined signal that is recognized only by the telephone  114  as a ringing signal. Additionally, the docking station  150  may send data in the form of an FSK signal to inform the user of the telephone  114  that the call is an intercom call and, optionally, which extension the call is from. At line  1112 , the docking station  150  recognizes an off-hook condition of the telephone  114  and stops the alerting signal. At step  1114 , the intercom call is complete.  
      Turning now to  FIG. 12 , operative components for providing an intercom in the docking station  150  are shown. The line-pair switch  202  is connected to premises telephone lines  1202 . An analog portable telephone  1208  and an analog wireline telephone  1206  also are connected to the telephone lines  1202 . The telephones  1208  and  1206  are well known in the art and therefore not discussed further.  
      The docking station  150  includes a DTMF detector  1210 , an off-hook detector  1212  and a ring generator  1214 , all of which are known in the art and therefore not discussed further. The DTMF detector  1210 , the off-hook detector  1212 , and the ring generator  1214  all are connected to both the line-pair switch  202  and the processor  208 . A ring button  1216  also is connected to the processor  208 .  
      When a user presses the ring button  1216 , the processor  208  causes the ring generator  1214  to start a ringing sequence on all connected analog telephone sets ( 1208  and  1206  in the example of  FIG. 12 ). When the ringing sequence starts, the processor  208  causes a SLIC  206  to turn off dial tone for a predetermined time (10 seconds, for example). If the off-hook detector  1212  detects an off-hook condition from any telephone on the lines  1202 , it informs the processor  208 . The processor  208  stops the ring generator  1214  and suppresses dial tone for the duration of the off-hook condition. An intercom telephone conversation may then be commenced.  
      Turning now to  FIG. 13 , an exemplary embodiment of a paging/intercom station set is shown, generally at  1300 , in accordance with another aspect of the present invention. The operative components of the paging/intercom station set  1300  generally comprise a line-pair switch  202 , an SLIC  206 , and a processor  208 , all of which are described above in connection with  FIG. 2 . A DTMF detector  1210 , a dialer circuit  1310 , and an FSK generator/receiver  1312  all are connected to the line-pair switch  202  and the processor  208 . Further, a ringing generator  1314  is connected to the processor  208  and to an audio device  1316  (i.e., a bell, a speaker, etc.), in order to provide an audible alerting signal. An LCD display  1318  and an intercom button  1320  also are connected to the processor  208 .  
      In accordance with this exemplary embodiment, a user causes the paging/intercom station set  1300  to go off hook by pressing an intercom button  1320 . Alternatively, the user may enter a code on a DTMF keypad (not shown, but well known in the art), such as “##.” This action causes the processor  208  to turn off dial tone and digit dialing at the SLIC  206 . The number of the intercom telephone (called telephone) then is entered (such as “4” for the telephone  1304 ). A DTMF detector  1210  in the called telephone detects the number and informs its processor  208 . That processor  208  recognizes that the call is for itself and causes a ringing generator  1314  to generate a signal at an audio device  1316 . When the called telephone goes off hook, the ringing signal is stopped. Further, the calling telephone can generate an FSK encoded signal at the FSK generator  1312 , indicating the calling extension (or other information). An FSK receiver  1312  at the called extension decodes the FSK signal and passes any data on to its processor  208 , which displays the data on a LCD display  1318 .  
      Turning now to  FIG. 14 , a further exemplary embodiment of an intercom/paging telephone is illustrated, generally at  1400 . As in the previous embodiments, the intercom/paging telephone  1400  is connected to intercom telephones  1302  and  1304  via telephone lines  1202 . The telephone lines  1202  are connected to the intercom/paging telephone  1400  at a line-pair switch  202 . The line-pair switch  202  is connected to a SLIC  206 , which is connected to a processor,  208 , as described above. A DTMF detector/generator  1210 , an off-hook detector  1212 , an FSK generator/receiver  1312 , and a ringing generator  1314  all are connected to the line-pair switch  202  and are under the control of the processor  208 . An audio device  1316  is connected to a ringing generator  1314 . An LCD display  1318 , an intercom button  1320 , and a paging button  1410  are connected to the processor  208 .  
      In the exemplary embodiment of  FIG. 14 , the intercom/paging telephone  1400  is programmed with an intercom number, such as “4,” and also is programmed with a paging number, such as “0.” The off-hook detector  1212  looks for an off-hook condition on the lines  1202 . In response to detecting an off-hook condition, the off-hook detector  1212  informs the processor  208 , which causes the DTMF detector/generator  1210  to listen for DTMF signals. Responsive to detecting a “4” or a “0,” the processor  208  activates the ringing generator  1314 , which causes the audio device  1316  to make an audible alerting signal. When the telephone  1400  goes off hook, the processor  208  causes the ringing generator  1314  to stop.  
      Further, the intercom/paging telephone  1400  may be equipped with direct buttons for intercom  1320 , for paging  1410 , or both. Activation of any of these buttons causes the processor  208  to generate an appropriate code at the DTMF detector/generator  1210 .  
      According to another embodiment of the present invention, the user may use one of the landline telephones  110 ,  112 ,  114  to make a call by inputting a telephone number to be called and continuously holding down or manipulating a key corresponding to the last digit of the called telephone number. The processor  208  of the docking station  150  is programmed to recognize that when the last digit of a telephone number is held for a predetermined period of time (e.g., 5 seconds or between 5 to 10 seconds) inputting of the telephone number is completed. The processor  208  then functions to control the docked mobile telephone  130  to dial or call the telephone number.  
      According to still another embodiment of the present invention, the docking station  150  of  FIG. 1  functions to enable the landline telephones  110 ,  112 ,  114  connected to the docking station  150  to send and receive “walkie-talkie” or PTT-type messages. In this embodiment, the mobile telephone  130  connected to the docking station  150  is a PTT-enabled telephone (e.g., a Nextel mobile telephone). Conventionally, users of PTT-enabled mobile telephones communicate with one another by holding down a PTT button when speaking and releasing the PTT button when listening. Landline telephones, however, do not have any hardware equivalent to a PTT button. To remedy this deficiency, the software/firmware of the processor  208  of the docking station  150  is programmed to recognize that when a predefined key or button of a landline telephone  110 ,  112 ,  114  is activated or when a hook switch (not shown) is toggled, the call is a PTT-type call.  
      More specifically, as shown in the flow charts of  FIGS. 15A and 15B , when the mobile telephone  130  docked in the docking station  150  is a PTT-enabled telephone, and when a PTT-type call is sent to the mobile telephone  130 , the landline telephones  110 ,  112 ,  114  announce the call with a distinctive ring or cadence (S 1 ). This enables a user (e.g., a callee) to know that the call is a PTT-type call and not a standard telephone call. The user may answer the call conventionally using the docked mobile telephone  130 , or the user may answer the call using any of the landline telephones  110 ,  112 ,  114  connected to the docking station  150 . To answer the call using one of the landline telephones  110 ,  112 ,  114 , the user picks up the handset and will hear the caller speak (S 2 ). When the user wants to speak, the user pushes and releases the predefined button of the landline telephone (S 3 ). Optionally, instead of pushing the predefined button, the user may toggle a hook switch (not shown) of the docking station  150 . At this point the user may speak to the caller (S 4 ). When the user is finished speaking and wants to listen to the caller&#39;s response (S 5 ), the user pushes and releases the predefined button again (S 6 ) or toggles the hook switch again. That is, unlike conventional PTT-type calls in which the user must hold down a PTT-button in order to transmit speech, the docking station  150  allows the user merely to push and release the predefined button (or toggle the hook switch) before the user starts to speak, to enable speech transmission, and then to push and release the predefined button (or toggle the hook switch) when the user is finished speaking, to enable reception of a response. This increases the convenience and improves the ergonomics of a PTT-type call, because the user does not have to hold down a PTT-button when using one of the landline telephones  110 ,  112 ,  114  for a PTT-type call.  
      In order to use one of the landline telephones  110 ,  112 ,  114  to initiate a PTT-type call via the docked PTT-enabled mobile telephone  130 , the user picks up the handset of one of the landline telephones  110 ,  112 ,  114  to make it go off-hook (S 11 ). The user then dials the number for the callee (S 12 ). Dialing may involve, for example, inputting the callee&#39;s PTT identification number, for example. To indicate that the call is a PTT-type call, the user then presses and releases the predefined button (S 13 ) or toggles the hook switch. At that point, the docking station  150  controls the docked mobile telephone  130  to place the PTT-type call (S 14 ). The callee is alerted about the incoming call, and the user then listens for the callee to answer. After the callee answers the call (S 15 ), the user presses and releases the predefined button (S 16 ) or toggles the hook switch and then commences speaking (S 17 ). When the user is finished speaking and wants to hear a response from the callee (S 18 ), the user presses and releases the predefined button again (S 19 ).  
      Preferably, the predefined button is a Flash button, which is commonly found on standard landline telephones. The processor  208  of the docking station  150  is programmed to recognize that when the Flash button is used or when the hook switch is toggled on one of the landline telephones  110 ,  112 ,  114 , a PTT-type call is taking place. The processor then functions to control the docked PTT-type mobile telephone  130  to transmit speech and receive responses in accordance with signals from the Flash button or the hook switch.  
      According to another embodiment of the present invention, one of the landline telephones  110 ,  112 ,  114  may be used to initiate a “barge-in” PTT-type call via the docked PTT-enabled mobile telephone  130 . A barge-in PTT-type call is one in which the callee does not hear an alert about an incoming call, but instead hears the user (caller) directly. That is, the callee does not have to answer a barge-in PTT-type call, because the user&#39;s voice is heard as soon as a connection is made to the callee&#39;s telephone. To initiate a barge-in PTT-type call, the user picks up the handset of one of the landline telephones  110 ,  112 ,  114  to make it go off-hook (S 11 ). The user then dials the number for the callee (S 12 ). To indicate that the call is a PTT-type call, the user then presses and releases the predefined button (S 13 ) or toggles the hook switch. At that point, the docking station  150  controls the docked mobile telephone  130  to place the PTT-type call (S 14 ). The user can immediately start speaking (S 17 ) and the callee will hear the message. When the user is finished speaking and wants to hear a response from the callee (S 18 ), the user presses and releases the predefined button again (S 19 ).  
      According to yet another embodiment of the present invention, the user may select whether to initiate a barge-in PTT-type call or alerted PTT-type call by activating another button in addition to the predefined button. For example, in step S 12 , the user may press and release the # button and then the flash button to indicate a barge-in PTT-type call. If the user presses and releases the flash button without pressing and releasing the # button first in step S 12 , then the user has selected to initiate an alerted PTT-type call.  
      According to a further embodiment of the present invention, the docking station  150  is equipped with a built-in telephone with a handset (not shown). The built-in telephone functions as one of the landline telephones  110 ,  112 ,  114  connected to the docking station  150 , and thus may be used to send/receive calls via the docked PTT-type mobile telephone  130 . Optionally, the built-in telephone, the handset, or both may be equipped with a PTT button that performs functions corresponding to the functions performed by a PT button on a typical PTT-type mobile telephone known in the art. For example, the PTT button of the built-in telephone or the handset may be held down by a user when speaking and released when the user is finished speaking, similar to the PTT button of a typical PTT-type mobile telephone.  
      It is to be understood that the above-described embodiment is merely illustrative of the present invention and that many variations of the above-described embodiment can be devised by one skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.