WO2001050618A1

WO2001050618A1 - Cellular telephone docking station

Info

Publication number: WO2001050618A1
Application number: PCT/US2001/000310
Authority: WO
Inventors: John B. Clayton, Iv; Kenneth Holberger; Roderick B. Sullivan, Jr.; Michael M. Hoeffler
Original assignee: Vox2, Inc.
Priority date: 2000-01-05
Filing date: 2001-01-05
Publication date: 2001-07-12
Also published as: AU2630201A; WO2001050618A8

Abstract

A system for providing cellular network (26) access to a land-line telephone connected to premises wiring (16) having a first telephone-line and a second telephone-line includes a land-line interface for connection to at most the first telephone-line of the premises wiring. The system also includes a cellular-telephone interface (20a) for connection to a cellular telephone (22a) having access to the cellular network (26), and a controller establishes an audio connection between the cellular-telephone interface and the land-line interface in response to status information provided to the controller by the cellular interface and the land-line interface.

Description

CELLULAR TELEPHONE DOCKING STATION

REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Serial No.

60/174,517, filed January 5, 2000, the contents of which are herein incorporated by reference in their entirety.

FIELD OF INVENTION

This invention relates to cellular telephony, and in particular, to the interfacing of cellular networks with land-line networks.

BACKGROUND When erecting a structure intended for human occupancy, it is a customary practice to incorporate telephone wiring into the walls of the structure. The underlying assumption driving this practice is that virtually any such structure will ultimately be connected to a land-line telephone network. Since the labor cost of snaking telephone wiring through existing walls is so high, it makes economic sense to incur the cost of wiring a structure up front rather than adding the telephone wires after the fact.

In some cases, however, it also makes economic sense to refrain from connecting a structure to a land-line telephone network. For example, in a vacation home, the telephone may be used sporadically for only a few months of the year. For the remainder of the year, monthly telephone access fees continue to accrue, even though the telephone may be idle.

The telephone wires used to wire most structures have four separate conductors for supporting two separate telephone lines. Thus, virtually all new construction comes pre- wired for two separate telephone lines. Nevertheless, in many cases, the second pair of conductors remains idle because of the need to pay additional telephone access charges for the second line.

The advent of cellular telephony has provided some relief from the foregoing difficulties. In the case of a vacation home, one can forego connecting the premises wiring to a land-line network altogether. Instead, one can obtain telephone service on an as-needed basis by simply bringing one's cellular telephone to the vacation home. In the case of a home requiring a second line, one now has the alternative of using cellular telephone as the second line. One disadvantage of using a cellular line in the foregoing manner is that the cellular telephone must be readily available at the moment one wishes to place or receive a call. Unless one is willing to carry the cellular telephone all over the house, it may be necessary to rummage through several rooms within the house to locate the cellular telephone. A second disadvantage of using a cellular line in the foregoing manner is that devices such as fax machines, speaker phones, answering machines, and data communication modems cannot readily be connected to the cellular line.

SUMMARY

The invention provides for the connection of cellular telephone to premises wiring thereby enabling the use of conventional telephones connected to the premises wiring for communication over the cellular network.

A system according to the invention includes a land-line interface connected to premises wiring having first and second telephone lines. The land-line interface provides a connection to only the first telephone-line of the premises wiring. This leaves the second telephone-line free for other uses.

The system also includes a cellular telephone interface that can connect to a cellular telephone having access to a cellular network. In one embodiment, the cellular- telephone interface connects to a cellular telephone by providing electrical contacts that engage with corresponding electrical contacts on the cellular telephone. However, the cellular telephone interface can also connect to the cellular telephone by a wireless link.

The land-line interface and the cellular-telephone interface are linked by a controller that establishes an audio connection between the cellular-telephone interface and the land-line interface. The controller does so in response to status information provided to it by the cellular interface and the land-line interface.

In one embodiment of the invention, the controller can include an input port for receiving a sequence of tones from the land-line interface. The sequence of tones can include a first sub-sequence indicative of a telephone number, followed by a second sub-sequence for instructing the cellular telephone to send instructions representative of the first sub-sequence to the cellular network. The controller also includes a control signal output through which it transmits, in response to the sequence of tones, a control signal to the cellular telephone. The control signal represents instructions causing the cellular telephone to establish a connection to the telephone number indicated in the first sub-sequence of tones.

The system optionally includes a switch having a first setting for selecting the first telephone-line and connecting the land-line telephone to the land-line interface, and a second setting for selecting the second telephone-line and disconnecting the land- line telephone from the land-line interface. However, where the land-line telephones are two-line telephones, such a switch need not be separately provided. Similarly, if the second telephone-line is not connected to a land-line network, a switch is not necessary since all communication will take place through the first telephone-line.

The land-line interface can be a subscriber-line interface circuit, or "SLIC". The SLIC can communicate audio information through analog input and output audio ports connected to corresponding analog ports on the cellular-telephone interface. The audio input port of the SLIC can also be connected to an analog output audio port of the controller. This allows the controller to synthesize a tone and inject it into the premises wiring. The analog audio output port of the SLIC can also be coupled to an analog audio input port of the controller, thereby enabling the controller to receive DTMF tones from the premises wiring.

In one aspect of the invention, the telephone communicates over a LAN. When this is the case, the system includes a network interface to a local-area network with which the land-line telephone is in data communication.

The cellular-telephone interface typically communicates with the cellular telephone by securing the cellular-telephone to an electrical contact disposed in a docking receptacle. However, a cellular telephone can be docked, in a logical sense, whenever it is in communication with a docking station, regardless of the manner in which communication takes place.

In one embodiment, communication associated with docking is established over a short-range radio link. In this case, the cellular-telephone interface includes an antenna, an RF transmitter coupled to the antenna for providing a signal to the antenna for reception by the cellular-telephone, and an I/O controller in communication with the RF transmitter and the controller for providing communication to the land-line interface.

In one embodiment, the controller includes status ports for receiving land-line status information from the land-line interface and cellular-line status information from the cellular-telephone interface. The controller also includes control ports for providing land-line control signals to the land-line interface and cellular-line instructions to the cellular-telephone interface. In this embodiment, a processor associated with the controller determines what instructions to send in response to the status information is performed by a processor associated with the controller.

A controller can also include a tone generator connected to the land-line interface for synthesizing an audible tone and providing the audible tone to the land- line telephone in response to instructions from the processor. The tone generator can be a pulse-width modulator coupled to a filter, or it can be a pulse-code modulator. Examples of tones generated by the tone generator include dial tones, a busy signals, and a glare-warning signals.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

Other features and advantages of the invention will be apparent from the following detailed description and the accompanying drawings in which:

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a docking station connecting land-line telephones to a cellular network; FIG. 2 shows the operation of the docking station of FIG. 1 when making an outgoing call;

FIG. 3 shows the operation of the docking station in FIG. 1 when receiving an incoming call;

FIG. 4 shows the docking station of FIG. 1 in a configuration in which land- line telephones connect to either the cellular network or a land-line network;

FIG. 5 is a circuit diagram of one of the switches in FIG. 4;

FIG. 6 shows the docking station of FIG. 1 sharing a telephone line with several other docking stations;

FIGS. 7A-7C illustrate one protocol through which the docking stations of FIG. 6 communicate with one another;

FIGS. 8A-8C illustrate another protocol through which the docking stations of FIG. 6 communicate with one another;

FIG. 9 is a block diagram of the docking station of FIG. 1;

FIG. 10 is a more detailed schematic of the docking station of FIG. 1;

FIG. 11 is a schematic diagram of the docking station of FIG. 1 but adapted to communication with an IP telephone over a LAN;

FIG. 12 is a schematic diagram of the docking station of FIG. 1 but adapted to communication with a cellular telephone across a wireless link; and

FIG. 13 is a schematic diagram of a docking station from FIG. 6.

DETAD ED DESCRD7TION

FIG. 1 shows a system 10 that makes telephone service available to one or more land-line telephones 12a, 12b connected to a first line 14a of the premises wiring 16 of a building 18. The system provides a docking station 20a resembling a cellular telephone recharging cradle. Although shown in FIG. 1 as connected to the first line 14a, the docking station 20a connects to either the first line 14a or a second line 14b of the premises wiring 16. To provide telephone service to the land-line telephones 12a, 12b, one inserts a cellular telephone 22a into a docking receptacle 24a of the docking station 20a. In the configuration shown in FIG. 1, the docking station 20a enables land- line telephones 12a, 12b to communicate through a cellular network 26.

In the system shown in FIG. 1, two land-line telephones 12a, 12b comiect to the first line 14a. However, it will be understood that other telephonic devices can be connected to the first line 14a. For example, one can connect a fax machine or a data communication modem to the first line 14a without altering the operation of the invention. Consequently, as used herein, the term "land-line telephone" is intended to encompass all devices adapted to communicate over a land-line network. Such devices include fax machines, speaker phones, answering machines, caller ID units, and data communication modems, and telephones that communicate over a LAN.

The premises wiring 16 illustrated in FIG. 1 is standard telephone wiring for 2500-type phones typically found in most homes and offices. Such wiring includes four conductors identified by insulating jackets in red, green, black, and yellow. By default, land-line telephones are connected to the red and green conductors. Without loss of generality, the red and green conductors will therefore be referred to collectively as "Line 1." The black and yellow conductors will be collectively referred to as "Line 2." The first line 14a referred to above can be Line 1, in which case the second line 14b is Line 2. Conversely, the first line 14a can be Line 2, in which case the second line 14b is Line 1.

FIG. 2 illustrates the operation of the docking station 20a in the context of an outgoing call placed by a calling party using one of the land-line telephones 12a, 12b to reach a called party. The following discussion of FIG. 2, and the discussions of all figures showing flow charts, liberally use the word "step." This is done to improve the readability of the specification and to make clear precisely what portions of the figures are referred to in their corresponding discussions. The word "step" is used only in the sense of its customary English meaning as one of a series of actions or measures taken to achieve some purpose. In particular, the word "step" is not used as a specialized talisman to invoke any presumption under 35 U.S. C. 112. A calling party who picks up a land-line telephone, 12a, 12b creates an off- hook condition on the first line. As shown in FIG. 2, the docking station 20a continuously monitors the first line to determine if such an off-hook condition exists (step 28). Upon detection of an off-hook condition (step 30), the docking station 20a generates a dial tone (step 32). If the calling party hangs up the land-line telephone 12a, 12b, the docking station 20a detects the absence of an off-hook condition (step 34) and reverts to its line-monitoring state (step 28).

If the calling party dials a first sequence of digits representative of a telephone number, the docking station 20a detects that first sequence of digits (step 36). The docking station 20a then awaits instructions indicating that the dialing is complete and the call should be placed. If the calling party dials a second sequence of selected digits indicating completion of the dialing process, the docking station 20a detects this second sequence of selected digits (step 38) and, in response, provides instructions to the cellular telephone 22a to initiate a call to the called party as specified in the first sequence of digits (step 40). If the called party answers, the docking station 20a provides service to the calling party using the land-line telephone 12a, 12b (step 42) for as long as the calling party and the called party have their respective handsets off-hook.

The second sequence of digits is thus the equivalent of the "send" key found on most cellular telephones. The second sequence of digits can be dialed manually or automatically using a programmable speed-dial button found on many modern land-line telephones. The second sequence of digits can be as short as one digit. For example, the "#" key by itself, or the "#" key by itself, can constitute the entire second sequence of digits.

The use of a second sequence of digits, such as the "#" key, is advantageous because it eliminates the requirement of detecting the last digit dialed. Algorithms for detecting the last digit dialed tend to either count the number of digits dialed or wait for a predetermined time-out period. An algorithm that counts the number of digits dialed cannot easily be used for international calls in which the number of digits in a telephone varies. An algorithm that relies on a time-out period introduces a short, but annoying delay in the dialing process. Both these difficulties are circumvented in the present invention by enabling the docking station 20a to implement the equivalent of a "send" key on a conventional land-line telephone.

The docking station 20a periodically monitors the line to detect whether one of the calling party and the called party has hung up (steps 44 and 46). If the calling party hangs up (step 44), the docking station 20a sends an instruction to the cellular telephone 22a that is equivalent to pressing the "end" key found on most cellular telephones (step 48). If the called party hangs up (step 46), the docking station 20a again generates a dial tone (step 32).

FIG. 3 shows the operation of the docking station in the context of an incoming call. As shown in FIG. 3, the docking station 20a continuously monitors the cellular telephone 22a for incoming calls on the cellular network 26 (step 50).

Upon detection of an incoming call (step 52), the docking station 20a places a call-detected signal on the first line 14a (step 54). This signal manifests itself in one of three ways depending on the status of the land-line telephone 12a. If the land-line telephone 12a is on-hook, the call-detected signal manifests itself by causing the land- line telephone 12a to ring. If the land-line telephone 12a is engaged in a call, the call- detected signal manifests itself as a call- waiting signal on the ear-piece of that land-line telephone 12a, 12b.

When a called party picks up the telephone 12a to make an outgoing call before the telephone 12a has had a chance to ring on an incoming call, the two parties are connected to each other without knowing it, with potentially embarrassing consequences to one or both parties. This phenomenon, referred to as "glare," is addressed by using the call-detected signal to provide one or more audible beeps in the ear-piece of the called party's land-line telephone 12a when the land-line telephone 12a is off-hook but has not yet finished dialing. This last state occurs when the docking station 20a detects an incoming call (step 52) after it has detected that a calling party has picked up the handset (step 30) but before the docking station has placed a call (step 40).

When the called party picks up the ringing land-line telephone 12a, 12b to answer it, the docking station 20a detects the resulting off-hook condition on the first line 14a (step 56) and establishes a connection between the cellular telephone 22a and the land-line telephone 12a, 12b (step 58).

The docking station 20a periodically monitors the first line 14a to detect whether one of the calling party and the called party has hung up (steps 60 and 62). If the called party hangs up (step 60), the docking station 20a sends an instruction to the cellular telephone 22a that is equivalent to pressing the "end" key found on most cellular telephones (step 64). If the calling party hangs up (step 62), the docldng station 20a generates a dial tone (step 66) while continuing to monitor the cellular telephone 22a for incoming calls (step 50).

When a cellular telephone 22a receives a telephone call, it will also typically receive caller-ID information such as the caller's telephone number and name. In one aspect of the invention, the docking station 20a requests the caller-ID information from the cellular telephone 22a and injects that information as a burst of data between the first and second rings of the land-line telephones 12a, 12b. This technique simulates a caller-ID transmission as carried out on a land-line network.

The configuration shown in FIG. 1 uses a cellular telephone 22a as an alternative to land-line telephone service. For example, the docking station 20a shown in FIG. 1 can bring telephone service to a remote home having premises wiring 16 for telephones but lacking a land-line connection to a telephone network. The configuration shown in FIG. 1 might also be used to bring telephone service to a mobile structure, for example a yacht or cruise ship.

In many cases, however, a homeowner who subscribes to both a land-line service and cellular service may want a second telephone line. Such a homeowner may understandably be reluctant to pay yet another monthly telephone access fee for a second line. The system shown in FIG. 4 addresses the needs of such a homeowner.

In FIG. 4, the second line 14b of the premises wiring 16 is connected by a land- line link to a land-line network 68 in the conventional manner. The first line 14a of the premises wiring is connected to the docking station 20a as already described in connection with FIG. 1. The embodiment shown in FIG. 4 includes switches 70a, 70b associated with land-line telephones 12a, 12b for connecting the telephones 12a, 12b to either the first line 14a or the second line 14b. In a two-line telephone, such a switch is already built into the telephone. In the case of a single-line telephone, such switches are commercially available from a variety of manufacturers.

With a switch 70a configured to connect its associated land-line telephone 12a to the second line 14b, a user who picks up the telephone 12a and simply dials will 5 obtain service from the land-line telephone network 68. To place a call through the cellular network 26, the user would have to set the switch 70a to connect its associated telephone 12a to the first line 14a. Conversely, when the switch 70a is set to connect its associated land-line telephone 12a to the first line 14a, a user who picks up the telephone 12a and simply dials will obtain service through the cellular network 26. To o place a call through the land-line network 68, such a user would have to set the switch 70a to connect its associated telephone 12a to the second line 14b.

In some cases, a user who places a call on the second line 14b may forget to reset the switch to the first line 14a after competing the call. To avoid this difficulty, one embodiment of the switch 70a provides for a default line. In such a switch, an 5 automatic reset causes the switch to revert back to the default line at the end of a call.

Switches having the foregoing properties are available from a variety of manufacturers. One such switch is available from TT Systems of New York and sold under the trademark "DIRECT-A-CALL." A circuit diagram for a representative switch having these properties is provided in FIG. 5.

0 The docking station 20a can generate a distinctive ring that distinguishes its calls from those arriving by way of the land-line network 68. This enables a user to determine, on the basis of the ring, whether the call is arriving over the cellular network 26 or over the land-line network 68.

In the case of an incoming call, a user may pick up the ringing telephone's 5 handset without setting its associated switch 70a to a position that corresponds to the line carrying the incoming telephone call. It is therefore preferable, in such a case, that a switch 70a detect the line carrying the incoming call and set itself to select that line for the duration of the call. An advantage of associating switches 70a ,70b with each telephone rather than providing a single switch at the docking station 20a is that in such a system 10, one telephone 12a can use the first line 14a at the same time that a second telephone 12b uses the second line 14b. This is not possible in a system in which a switch is located at the docking station because both telephones would then have to use the same docking station as a switch to reach their respective lines.

As shown in FIG. 6, a plurality of docking stations 20a-d may be connected to the first line 14a. In the case of incoming calls, the docking station through which an incoming call arrives takes control of the first line 14a. A user can configure each docking station 20a-d to emit a distinctive ring. This enables a user to quickly identify the source of an incoming call.

In the context of an outgoing call, it is necessary to identify one docking station 20a as a "primary station." A primary station 20a is that docking station that handles outgoing calls when the user makes an outgoing call. All other docking stations 20b-d are referred to as "secondary stations."

A docking station becomes either a primary or a secondary station on the basis of a priority assigned to that docking station by a user. In one embodiment, each docking station 20a-d has a switch through which a user assigns it a numerical priority. In another embodiment, the docking stations 20a-d implement instructions for converting a sequence of dialed tones into an assignment, of a numerical priority.

When several docking stations 20a-d are connected to a common line 14a as shown in FIG. 5, it is preferable that they be able to communicate with each other. There are at least two reasons for this. First, a docking station 20a knows only its own priority. It cannot determine, from its own priority, whether it has the highest priority of all the docking stations 20a-d. Second, a docking station 20a can only make an outgoing call when a cellular telephone is docked in that docking station. Hence, if a user removes the cellular telephone docked in the primary station, the remaining docking stations 20a-d must determine among themselves which one of them is to act as the primary station in the absence of the cellular telephone normally docked in the primary station. To coordinate line usage, the docking stations 20a-d negotiate for line access by exchanging messages over the second line 14b of the premises wiring 16. This eliminates the need to provide additional wiring specifically for this task. These messages are carried by two sequential 50 ms DTMF tones separated by 50 ms. The messaging system uses the "A," "B," "C," and "D" tones to support up to sixteen different messages.

FIG. 7A shows the flow of messages that occurs when a user removes a cellular phone 22a from a primary station 20a (step 76). Upon removal of its cellular telephone 22a, the primary station 20a broadcasts a PRIMARY UNDOCKED message (step 78). In response to the receipt of the PRIMARY UNDOCKED message, each secondary station 20b-d identifies itself and generates a SECONDARY TAKES OVER message after a delay determined by its priority (step 80).

In one embodiment, the secondary station having the highest priority will respond last, thereby canceling responses from other secondary docking stations. In another embodiment, the secondary station having the highest priority responds first, thereby precluding other secondary docking stations from taking control of the line.

In response to the SECONDARY TAKES OVER message, the primary station 20a sends a SECONDARY TAKES OVER ACK message. The secondary station having the highest priority then becomes an acting primary station until the cellular telephone 22a is again docked in the primary station 20a (step 88).

FIG. 7B illustrates messages exchanged when a user returns the cellular telephone 22a to the primary station 20a (step 90). In response to the docking of its associated cellular telephone 22a, the primary station broadcasts a PRIMARY DOCKED message over the first line 14a (step 92). In response to the PRIMARY DOCKED message, the acting secondary station, designated as described in connection with FIG. 7A, cedes control of the first line 14a back to the primary station 20a (step 94).

FIG. 7C shows how a secondary station 20b borrows the first line 14a from the primary station 20a when a call arrives on cellular telephone 22b docked at that secondary station 20b (step 96). As shown in FIG. 7C, upon receipt of a call, the secondary station 20b issues a SECONDARY REQUEST LINE message to the primary station (step 98). The primary station then determines if the first line 14a is in use (step 100).

If the first line 14a is not in use, the primary station temporarily relinquishes control of the line by issuing a LINE AVAIL message (step 102). The secondary station then takes control of the line and makes the incoming telephone call available to the user (step 104). When the secondary station no longer needs the first line, for example when the user completes the call and hangs up, the secondary station cedes control of the first line back to the primary station by sending a SECONDARY RELEASE LINE message (step 106).

If the first line 14a is in use, the primary station sends a LINE UNA VAIL message to the secondary station (step 108). In this case, the secondary station ignores the call (step 110). The SECONDARY REQUEST LINE message and the LINE UNA VAIL message are, however, available for use as call- waiting tones to be provided to the user at the primary station 20a.

In an alternative embodiment, the docking stations broadcast their priority values to each other, as shown in FIGS. 8A-8C.

FIG. 8A shows a method for ensuring that no two docking stations have the same priority value. The method begins with the user setting a priority value of a first docking station (step 112) in the manner already described above. The user might do so when installing a new docking station. Alternatively, the user may want to change the priority of an existing docking station. As will be apparent from the following description, there is no guarantee that the first docking station will ultimately have that priority value. For this reason, that priority value is referred to as a "proposed" priority value.

In response to the change in its priority, the first docking station broadcasts a RING SELECT BEGIN message to all other docking stations (step 114). This initiates a negotiation interval during which the remaining docldng stations are expected to broadcast their respective priority values. During this negotiation interval, no incoming calls are taken and no other docking station can issue a RING SELECT BEGIN message.

The first docking station follows up its RING SELECT BEGIN message with a PRIORITY n message, where n is the proposed priority value of the first station (step 116). The remaining docking stations compare this proposed priority value with their own priority values (step 118). If a remaining docking station already has a priority value equal to the proposed priority value, that remaining docking station sends a PRIORITY nACK message. The first docking station thus monitors the first line for the occurrence of a PRIORITY n ACK (step 120).

If no PRIORITY n ACK message is received (step 120), the first docking station concludes that the proposed priority value is available (step 122). The first docking station then sends a RING SELECT END message to end the negotiation session and restore the system to its normal operating state (step 124).

If a PRIORITY n ACK message is received from a remaining docking station, (step 120) then the proposed priority value is unavailable (step 128). Under these circumstances, the first docking station can notify the user (step 126) before sending a RING SELECT END message to end the negotiation session and restore the system to its normal operating state (step 124). Alternatively, the first docking station can adjust its priority number either up or down until it finds a priority value that does not cause any other docking station to transmit a PRIORITY nACK message.

In one embodiment of a system having several docking stations sharing a common line, each station has a flag named PRIMARY which is either set to "on", in which case that station is the primary station, or set to "off," in which case that station is not the primary station. At any instant, only one station may have a PRIMARY lag set to "on." That station should be one having the highest priority value. To ensure that this is the case, each station periodically broadcasts a PRIMARY n message announcing its priority value. The responses of the remaining stations to the periodic PRIMARY n messages received from the any one station are shown in FIG. 8B.

The method shown in FIG. 8B begins with the transmission of a PRIORITY n message by a first station (step 130). In response, a second station determines if its corresponding cellular telephone is docked (step 132). If its corresponding cellular telephone is not docked, it cannot receive any calls. Hence, it is not eligible to be the primary station and therefore does nothing further. If the station's corresponding cellular telephone is docked, then the second station compares its own priority with that of the first station, as broadcast on the PRIORITY n message (step 134).

If the priority value of the second station is lower than that broadcast in the

PRIORITY n message, then the second station sets its PRIMARY flag to "off," thereby indicating that it is not entitled to primary status (step 136).

If the priority value of the secondary station is equal to that broadcast in the PRIORITY n message, then, in a policy favoring incumbency, the second station decrements its priority value (step 138) and sets its PRIMARY ^'flag to "off," thereby indicating that it is not entitled to primary status (step 140).

Finally, if the priority value of the second station is greater than that broadcast in the PRIORITY n message, then that station waits a specified period, the length of which depends on that station's priority value (step 142). If, after than specified period, the second docking station has received no PRIORITY n messages announcing the existence of another docldng station with a higher priority, then the second docking station sets its PRIMARY flag to "on" (step 144) and announces its own priority value to the other stations by broadcasting a PRIORITY n message (step 146).

The method shown in FIG. 8B quickly identifies the docking station having the highest priority value. Additionally, the illustrated method is sufficiently robust to recover from process handles power outages, from the removal and reinstallation of docking stations, and from the removal and replacement of cellular telephones associated with the docking stations. The illustrated method also enables a system having multiple docking stations on a common line to be self-configuring upon installation.

Referring now to FIG. 8C, when a docking station detects an incoming call (step 148), that docking station broadcasts a CALL PROGRESS QUERY ^"to determine if the first line is already in use (step 150). If the docking station determines that a call is in progress (step 152), then the docking station ignores this call as described above in connection with FIG. 7C. If the docldng station determines that the line is available, it broadcasts a CALL START message (step 154). The call start message causes all other stations to halt their transmissions of PRIORITY N messages as described in connection with FIG. 8B.

The docking station then checks to see if it is the primary station for the system (step 156). If it is, the docking station establishes a connection between its corresponding cellular telephone and the first line. If it is not the primary station, the docking station waits for a CALL START ACK message from the primary station (step 160) before it establishes a connection between its corresponding cellular telephone and the first line.

In either case, once the telephone call is completed, the docking station releases the first line by sending a CALL COMPLETE message (step 162).

A wide variety of electronic configurations within the docldng station can provide the features described above. FIG. 9 shows a block diagram of one such configuration. The docking station 20a shown includes a land-line interface 164 that communicates status information concerning the land-line to a micro-controller 168. The docking station 20a also includes a cellular-telephone interface 166 that communicates status information concerning the cellular telephone to the microcontroller 168. In response to this status information, the micro-controller 168 sends control signals to both the cellular-telephone interface 166 and the land-line interface 164.

The cellular-telephone interface 166 and the land-line interface 164 have a two- way audio communication path 170 extending between each other. Among the instructions provided by the micro-controller 168 is an instruction to open this audio communication path 170 and to thereby enable a user of the land-line telephone 12a to communicate with a user on the cellular network through the docked cellular telephone 22a.

FIG. 10 shows one implementation of a docldng station 20a having the features described in FIG. 9. The docking station 20a includes a micro-controller in communication with both a cellular-telephone interface 166 and a land-line interface h the illustrated embodiment, the land-line interface 164 includes a subscriber line interface circuit 172 (SLIC) having a tip-and-ring port 174, audio input and output ports 176a, 176b, a land-line control port 178, and a land-line status port (labeled "DET" in the figure) 180.

The tip-and-ring port 174 is connected, through some intervening filters, to a line-selector switch 182. This line-selector switch 182 enables the land-line interface 164 to connect to either the first line 14a or to the second line 14b of the premises wiring 16. Note that this switch is not the same as the switches 70a, 70b associated with each of the telephones 12a, 12b connected to the premises wiring 16.

The land-line control port 178 and the land-line status port 180 are both connected to the micro-controller 168. Through the land-line status port 180, the SLIC 172 provides status information concerning the premises wiring 16 to the microcontroller 168. Such status information includes whether a land-line telephone 12a connected to the premises wiring 16 is off-hook or not. Through the land-line control port 178, the SLIC 172 receives instructions from the micro-controller 168. Such instructions include to instructions to generate a ringing voltage on the tip-and-ring port 174, thereby causing land-line telephones 12a, 12b comiected to the premises wiring 16 to ring. Such instructions also include instructions to connect the audio input and output ports 176a, 176b to the tip-and-ring port 174.

The illustrated cellular telephone 166 interface includes speaker and microphone ports 184a, 184b that are conventionally used to interface with car-kit microphones and speakers. As a result, use of these ports typically disables the cellular telephone's own microphone and speaker. By connecting the speaker and microphone ports 184a, 184b of the cellular-telephone interface 166 with the audio input and output ports 176a, 176b respectively, one establishes a two-way voice communication path between the cellular telephone 22a and the SLIC 172. In response to an instruction from the micro-controller 168, the SLIC 172 can connect this voice communication path 170 to the premises wiring 16 by way of its tip-and-ring port 174, thereby completing a two-way voice communication path between the cellular telephone 22a and land-line telephones 12a, 12b connected to the premises wiring 16. The cellular-telephone interface 166 includes a cellular-telephone-status port 186 that provides status information on the cellular telephone 22a. This status information includes information on whether the cellular telephone 22a is docked and ready to for use, information on whether there is an incoming call on the cellular telephone 22a, information indicating the source of that call, and information indicating whether or not the cellular telephone is engaged in a call or otherwise unavailable for use. Status information concerning the status of the cellular telephone is made available to the micro-controller 168 through its UART (Universal Asynchronous Receive/Transmit) RD port 188. The presence or absence of a cellular telephone 22a in the docking station 20a is apparent from a change in the base voltage level of the signal at the cellular-telephone-status port 186. This change is detected by the microcontroller 168 through a docked-detector port 200.

The cellular-telephone interface 166 also includes a cellular-telephone-control port 190 for receiving commands sent from the micro-controller 168. These commands, which the micro-controller 168 sends through its UART TD port 192, can include instructions to place a call to the location specified by the first sub-sequence of digits dialed by a caller, to initiate the call in response to the second sub-sequence of digits dialed by the caller, and to end the call in response to an on-hook condition on the telephone line connected to the tip-and-ring port 174.

In the illustrated embodiment, the cellular-telephone-status port 186 is the TD

Fbus port on the cellular-telephone interface 166. For some cellular telephones, however, the cellular-telephone-status port 186 is the MBus port 195 on the cellular- telephone interface 166. Similarly, for the illustrated embodiment, the cellular- telephone-control port 190 is the RD Fbus port on the cellular-telephone interface 166. For some cellular telephones, the cellular-telephone-control port 190 is the MBus port 195 on the cellular-telephone interface 166.

To accommodate this, the micro-controller 168 includes an Mbus-selection port 194 on which it places a bus-selection signal for selecting whether the UART ports 188, 192 of the micro-controller 168 will communicate to the cellular-telephone interface 166 through the pair of FBus ports 186, 190 or through an Mbus port 195. A high bus-selection signal on the Mbus-selection port 194 disables first and second buffers 196, 198 on the two FBus lines so as to block traffic between the Fbus ports 186, 190 and the UART ports 188, 192. At the same time, the high bus-selection signal enables third and fourth buffers 200, 202 that enable traffic to flow between the MBus port 195 and the UART ports 188, 192. Conversely, a low bus-selection signal enables the first and second buffers 196, 198 and disables the third and fourth buffers 200, 202, thereby blocking traffic between the UART ports 188, 192 and the MBus port 195 and allowing traffic between the FBus ports 186, 190 and the UART ports 188, 192.

The illustrated docking station also includes tone-generating elements for generating the various audio tones used to communicate status information regarding the cellular telephone 22a to someone attempting to place a call over the cellular network 26 using a land-line telephone 12a connected to the premises wiring 16. Such tones include dial tones, busy signals, and signals indicating the existence of a glare condition. In an alternative embodiment, shown in FIG. 6, tones generated by the tone- generating elements can be used to communicate with other docking stations 22b-d connected to the same line.

The tone generating elements include a PWM (pulse width modulator) port 204 on the micro-controller 168 that provides a sequence of pulses. The pulse sequence from the PWM port 204 is passed to a filter 206 that alters its spectrum to generate the desired tone. The desired tone is then provided to the audio input port 176a of the SLIC 172, which then passes it to the land-line telephone 12a through the tip-and-ring port 174 of the SLIC 172.

The tones generated by the tone generating elements can be selected to simulate those generate by the land-line network 68. Alternatively, it may be desirable to provide tones that are distinct from those provided by the land-line network 68 so that a caller can easily tell whether the land-line telephone 12a is connected to the land-line network or to the cellular network 26. The ability to alter the dial tones and ringing tones is also desirable for simulating tones in other countries that do not necessarily use tones identical to those used domestically.

The docking station 20a also includes a DTMF decoder 208 connected between the audio-output port 176b of the SLIC 172 and the micro-controller 168. The DTMF decoder 208 enables a caller to use the keypad of a land-line telephone 12a to send instructions to the micro-controller 168 by using sequences of tones. These sequences of tones may represent telephone numbers to be dialed on the cellular telephone 22a, a send command to be transmitted to the cellular telephone 22a, or instructions for configuring the docking station 20a. When appropriate, the micro-controller 168 5 incorporates instructions representing these tone sequences into the instructions that it provides to the cellular-telephone interface 166.

The micro-controller 168 selects control signals on the basis of status signals from both the SLIC 172 and the cellular-telephone interface 166. It does so by executing programmed instructions stored in the micro-controller 168. These o instructions implement the features described in connection with the discussion of FIGS. 2 and 3. The use of a programmable micro-controller 168 enables one to easily modify the operation of the docldng station without the need to modify hardware.

The cellular-telephone interface 166 shown in FIG. 9 is that associated with a cellular telephone sold under the trademark NOKIA. The details on the ports of the 5 cellulai-telephone interface 166 and the manner in which they interface with the microcontroller 168 are thus specific to this particular cellular telephone. These details can be expected to vary depending on the specific type of cellular telephone. What is important is that there be a connection between the micro-controller 168 and the cellular-telephone interface 166 that enables the micro-controller 168 to detect the 0 status of the cellular telephone 22a and that enables the micro-controller 168 to provide instructions to the cellular telephone 22a.

In another embodiment, the land-line telephone 12a is a telephone connected to a local area network. A docking station 20a for interfacing with such a telephone includes a LAN controller 210 as shown in FIG. 11. In the embodiment shown in FIG. 5 11 , a telephone connects to a 10/100 Base T port 212 on the LAN controller 210 through an RJ-45 port 214. The LAN controller 210 connects to the tip-and-ring port 174 of the SLIC 172 through an HPNA port 216 on the LAN controller 210. The HPNA port 216 provides signals that appear to the SLIC 172 to be coming from conventional premises wiring. In this embodiment, the SLIC 172 is unable to detect an 0 off-hook condition on the line. Consequently, the micro-controller 168 obtains this information directly from the LAN controller 210. With the foregoing exceptions, the remaining components of the docking station 20a operate in the same manner as already described in connection with FIG. 10.

A cellular telephone 22a typically has electrical contacts through which it communicates with the cellular-telephone interface 166. This communication occurs 5 upon docking the cellular telephone 22a in the docking station 20a so that corresponding electrical contacts in the docking receptacle 24 are in electrical communication with the electrical contacts on the cellular telephone 22a.

The word "docking" is not, however, restricted to the case in which a cellular telephone 22a is nestled in a receptacle 24a in the housing of a docking station 20a. o Instead, a cellular telephone 22a is "docked" in the docking station 20a when the docking station 20a is able to establish communication with the cellular telephone 22a. In particular, the docking station 20a and the cellular telephone 22a can engage in short-range wireless communication using a protocol known by the trade name BLUETOOTH. Such a docking station 20a can detect the presence of a nearby cellular 5 telephone 22a and thereafter send and receive signals through antennas built into the cellular telephone 22a and the docking station 20a.

A docking station adapted to connect to a cellular telephone 22a in this manner is shown in FIG. 12. The illustrated docldng station includes an RF controller 220 connected to an antenna 222. The RF controller 220 communicates with an I/O 0 controller 224 having an audio port 226 for passing audio signals to and retrieving audio signals from the cellular telephone 22a. These audio signals are provided to the SLIC 172 by way of the micro-controller 168 rather than by using the audio ports of the SLIC 172 as was the case in the embodiments shown in FIGS. 10 and 11.

As another alternative to physical coupling of a cellular telephone 22a to the 5 docking station 20a, a desktop charging cradle is used to hold and charge the cellular telephone 22a can include a connector for operably coupling with a docldng station 20a.

The docking station 20a provide a variety of convenience features. For example, the docldng station 20a can feature its own RJ-11 jack so that use of the 0 docking station 20a does not eliminate a telephone outlet from a home. The docking station 20a can also include a power supply and regulator that can recharge a docked cellular telephone 22a.

The docking station also provides user-configuration controls. These controls enable the user to select the type of ring generated by the SLIC 172 when the docking station receives an incoming cellular call, to designate a priority value for the docking station, and to select which line on the premises wiring connects to the tip-and-ring port of the SLIC 172. The user-configuration controls can be hardware, such as switches or sliders. Or, the user-configuration controls can be software switches implemented by the micro-controller 168 in response to instructions provided by the user through a suitable input medium, for example through DTMF tones generated by a telephone.

The docking station also features status indicators, such as light emitting diodes (LEDs), that indicate that the docking station has power, and if so, whether a cellular telephone 22a is docked in the docldng station and connected to its cellular network and whether the docking station is in-use.

Since different cellular telephones have different shapes and different arrangements of interface ports, the housing of the docking station can be tailored to conform to the shapes of different cellular telephones. Alternatively, a docking station manufacturer can provide individual adapters that couple different cellular telephones to a generic housing.

As noted above in connection with the discussion of FIG. 6, it is preferable that docking stations be able to communicate with one another so as to assure that only one docking station, namely the one with the highest priority, will place outgoing calls on the common telephone-line. In order to communicate with each other, each docking station must be able to send messages on the telephone-line, even if that docking station is not the primary station. Although the docking stations can, in principle, pass messages to each other through the tip-and-ring terminals of their respective SLICs, this is an undesirable method of achieving such access because the presence of more than one active SLIC on a telephone-line leads to unreliable behavior.

FIG. 13 shows an embodiment of a docking station 20a that can send and receive DTMF tones on the telephone-line without using the SLIC. In this embodiment, messages for other docking stations 20b-d are generated at the PWM port 204 and injected directly into the telephone-line. Similarly, DTMF tones received from other docking stations 20b-d are received through a direct connection between the DTMF decoder 208 and the telephone-line.

Having described the invention, and a preferred embodiment thereof, what we claim as new and secured by letters patent is:

Claims

1. An interface for coupling a cellular network to a land-line telephone connected to premises wiring, the interface comprising:

an off-hook detector for connection to said premises wiring for detecting an off-hook condition at said land-line telephone;

a dial-tone generator for connection to said premises wiring, said dial-tone generator providing a dial tone to said land-line telephone in response to said off-hook condition;

a processing system for connection to said premises wiring and to a cellular telephone having access to said cellular network, said processing system

generating dialing instructions for execution by said cellular telephone in response to a sequence of tones generated by said land-line telephone,

said sequence of tones including a first sub-sequence indicative of a telephone number and a second sub-sequence for instructing said cellular telephone to send instructions representative of said first sub-sequence to said cellular network.

2. The interface of claim L further comprising a glare detector for connection to said cellular telephone, said glare detector generating a first signal indicative of a connection across said cellular network between said cellular telephone and a calling party.

3. The interface of claim 2 wherein said glare detector is in communication with said processing system and said processing system is configured to provide a glare- warning signal to said land-line telephone in response to detection of said first signal from said call detector.

4. The interface of claim 1 further comprising a wireless interface for connecting said processing system to said cellular telephone.

5. The interface of claim 4 wherein said cellular-telephone interface is a wireless interface.

6. The interface of claim 1 wherein said premises wiring includes at least a first line and a second line independent of said first line, and said interface further includes a switch associated with said land-line telephone for connecting said land-line telephone to said first line.

7. The interface of claim 1 further comprising a suppression system coupled to said dial-tone generator for determining a relative priority of said interface and suppressing operation of said dial-tone generator on the basis of said relative priority.

8. The interface of claim 7 wherein said interface has an absolute priority and said suppression system includes a priority-broadcaster for placing a signal indicative of said absolute priority on said premises wiring.

9. The interface of claim 7 wherein said suppression system includes a priority- receiver for detecting a signal indicative of an absolute priority of a second interface in communication with said premises wiring.

10. The interface of claim 1 wherein said premises wiring is a local area network and said interface further comprises a network interface in communication with said processing system.

11. A system for coupling a cellular network to a land-line telephone connected to premises wiring having a first circuit and a second circuit, said system comprising:

a switch associated with said land-line telephone for connecting said land-line telephone to said first circuit;

an interface for coupling said cellular network to said first circuit, said interface including

an off-hook detector for connection to said premises wiring for detecting an off-hook condition at said land-line telephone; a dial-tone generator for connection to said premises wiring, said dial-tone generator providing a dial tone to said land-line telephone in response to said off-hook condition;

a processing system for connection to said premises wiring and to a cellular telephone having access to said cellular network, said processing system generating dialing instructions for execution by said cellular telephone in response to a sequence of tones generated by said land-line telephone.

12. A system for providing cellular network access to a land-line telephone connected to premises wiring having a first telephone-line and a second telephone-line, said system comprising:

a land-line interface for connection to at most said first telephone-line of said premises wiring;

a cellular-telephone interface for connection to a cellular telephone having access to said cellular network; and

a controller in communication with said land-line interface and said cellular- telephone interface, said controller establishing an audio connection between said cellular-telephone interface and said land-line interface in response to status information provided to said controller by said cellular interface and said land-line interface.

13. The system of claim 12, wherein said controller comprises

an input port for receiving a sequence of tones from said land-line interface, said sequence of tones including

a first sub-sequence indicative of a telephone number, and

a second sub-sequence for instructing said cellular telephone to send instructions representative of said first sub-sequence to said cellular network; and a control signal output for providing dialing instructions for execution by said cellular telephone in response to said sequence of tones.

14. The system of claim 12 further comprising a switch having a first setting for selecting said first telephone-line and connecting said land-line telephone to said land-line interface, and a second setting for selecting said second telephone-line and disconnecting said land-line telephone from said land-line interface.

15. The system of claim 12, wherein said land-line interface comprises a subscriber- line interface circuit.

16. The system of claim 15, wherein said subscriber-line interface circuit comprises input and output analog audio ports for connection to corresponding output and input analog audio ports on said cellular-telephone interface.

17. The system of claim 16 wherein said controller comprises an output analog audio port connected to said input analog audio port of said subscriber-line interface circuit for injecting a tone therein.

18. The system of claim 16 wherein said controller comprises an input analog audio port connected to said output analog audio port of said subscriber-line interface circuit for receiving a tone therefrom.

19. The system of claim 12 wherein said land-line interface comprises a network interface to a local-area network with which said land-line telephone is in data communication.

20. The system of claim 12 wherein said cellular-telephone interface includes a receptacle adapted to secure said cellular-telephone to an electrical contact disposed in said receptacle, said electrical contact providing communication between said cellular-telephone and said cellular-telephone interface.

21. The system of claim 12 wherein said cellular-telephone interface comprises

an antenna; an RF transmitter coupled to said antenna for providing a signal to said antenna for reception by said cellular-telephone; and

an I/O controller in communication with said RF transmitter and said controller for providing communication to said land-line interface.

22. The system of claim 12 wherein said controller comprises:

a land-line status port for receiving land-line status information from said land- line interface;

a cellular-line status port for receiving cellular-line status information from said cellular-telephone interface;

a land-line control port for providing land-line control signals to said land-line interface;

a cellular-line control port for providing cellular-line instructions to said cellular-telephone interface; and

a processor for selecting said cellular-line instructions and said land-line instructions in response to said land-line status information and said cellular-line status information.

23. The system of claim 22 wherein said controller comprises a tone generator connected to said land-line interface for synthesizing an audible tone and providing said audible tone to said land-line telephone in response to instructions from said processor.

24. The system of claim 23 wherein said tone generator comprises a pulse-width modulator coupled to a filter.

25. The system of claim 23 wherein said tone generator comprises a frequency-shift modulator.

26. The system of claim 23 wherein said audible tone is selected from the group consisting of a dial tone, a busy signal, a glare-warning signal, and a DTMF tone.

27. The system of claim 22 further comprising a DTMF decoder connected between said land-line interface and said controller for decoding a tone provided by said land-line interface.

28. The system of claim 22 further comprising

a DTMF decoder connected between said first telephone-line and said controller for decoding a tone present on said first telephone-line and

a tone generator connected to said first telephone-line for synthesizing an audible tone and placing said audible tone on said first telephone-line in response to instructions from said processor.

29. A method for providing cellular network access to a land-line telephone connected to premises wiring having a first telephone-line and a second telephone-line, said method comprising:

providing a land-line interface for connection to at most said first telephone- line of said premises wiring;

providing a cellular-telephone interface for connecting to a cellular telephone having access to said cellular network; and

establishing an audio connection between said cellular-telephone interface and said land-line interface in response to status information provided by said cellular interface and said land-line interface.