Abstract:
Messages are routed via a cellular communications network to multiple cellular communications receivers configured for answering calls placed to a common subscriber number, such that a message originated with a single cellular call may reach multiple recipients. The geographic area of message distribution may be controlled by selectively enabling different cell sites for calling particular subscriber numbers. The cellular receivers may have message storage capabilities for subsequent replay of received messages. Message storage may be provided by downloading messages to a conventional telephone answering device also connected for landline telephone call answering, thereby adding received cellular messages to recorded landline telephone messages.

Description:
This application is a Continuation of application Ser. No. 10/968,422 filed Oct. 18, 2004 which claims priority to the filing date of Provisional Application 60/496,945 filed Aug. 18, 2003 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains to the field of cellular wireless communications, and more particularly relates to one way wireless messaging using cellular communications networks. 
     2. State of the Prior Art 
     Cellular wireless communication systems are widely deployed and used for mobile telephone and other communications. Current use typically involves communications between individual subscribers each equipped with a handheld cellular telephone unit. The mobile units are each assigned unique telephone numbers and cellular communications are typically private between parties known to the cellular network. 
     The mobile handsets communicate via a cellular network which includes transponder cellsites each having a limited area of coverage and located so as to provide contiguous areas or cells of radio coverage over a larger area of service. The mobile handsets periodically transmit an identification signal which is used to locate the handset within the coverage area of one or more cellsites. The cellsites in turn are networked by trunk lines and are managed by a central control office. The location of active handsets received by all of the cellsites is known to the digital control system, so that a call placed to a particular wireless handset is placed, either from another mobile handset or from a conventional landline telephone, can be directed to a cellsite within radio range of the target handset. Two way communication, by landline for example, can then be established from the central control office to the appropriate cellsite, and the link completed by two-way radio communication between the cellsite and the handset. A detailed description of the operation of cellular communication networks is not necessary here as the topic is relatively complex and the information is available from publicly accessible sources. 
     Communications using such cellular networks are directed to specific subscribers, that is, to particular telephone numbers in a cellular telephone network. While messaging services exist for directing communications such as text messages to multiple recipients, each of the message recipients is also specified to the cellular network and known to the sender. 
     SUMMARY OF THE INVENTION 
     This invention provides a wireless messaging system which in a presently preferred embodiment makes use of a cellular communications network such including a number of cellsites for routing wireless messages to subscribers located within range of one or more of the cellsites. The cellular communications network may be of the type which is normally configured for monitoring the presence and location of individual active mobile handsets relative to different cellsites, such that messages or calls addressed to any one mobile number can be routed through an appropriate cellsite within range of the handset corresponding to that mobile number. For purposes of this invention, however, the cellular network is configured to operate without monitoring or verifying the presence of mobile handsets corresponding to mobile numbers assigned to a special category of subscriber here referred to as a broadcast subscriber. The broadcast subscriber is assigned a broadcast number which may be a particular mobile telephone number. Calls placed to a broadcast number are transmitted by one or more broadcasting cellsites without verifying the presence of a mobile handset corresponding to that broadcast number in the area covered by those one or more cellsites. The broadcasting cellsites are selected by the broadcast subscriber, for example, as part of a subscription agreement with the cellular network service provider. The one-way message broadcasting aspect of the cellular network may coexist with conventional two-way mobile communications by the network. 
     A number of cellular communications receivers are installed at recipient sites located within range of the broadcast cellsites. Each receiver is configured to accept calls routed to a broadcast number. Multiple such receivers may be configured to accept calls addressed to a same broadcast number through the broadcast cellsite or cellsites, such that multiple receivers may receive a call placed to a single broadcast number. A particular broadcast call or message may be broadcast through more than one cellsite so as to cover a wider geographic area of reception. Also, a broadcast call may be stored by the cellular network provider for subsequent broadcast through one or more cellsites, for example, during off-peak times of network usage. 
     In typical cellular communications networks the cellsite initiates a two-way call or communication with a mobile handset by assigning available frequencies or channels for the communication session, including a receive frequency and a transmit frequency for the mobile handset. The cellular receivers used in the preferred embodiment of the present invention lack transmission capability, so that no assignment of transmit frequency is needed. However, the receivers are preferably responsive to communications channel assignment control signal transmitted by the broadcasting cellsite, such that the receiver switches to a receive frequency assigned for the particular broadcast by the broadcasting cellsite, so that the cellular broadcast can be made over a frequency then available to the broadcasting cellsite. This assignment of receive frequencies can be made in the conventional manner currently employed with conventional two way mobile telephone handsets, for example. 
     The cellular receivers preferably have message storage capabilities, such as digital storage, for subsequent replay of received messages. 
     In one embodiment of the invention the cellular receivers are stand alone units with built in message playback capability, including for example, audio playback of voice messages, and for this purpose may have an audio amplifier and loudspeaker as part of the receiver unit. 
     In another embodiment of the invention the cellular receivers cooperate with a conventional telephone answering device of the type commercially available for answering calls to landline telephones and storing voice messages for subsequent replay. In this embodiment the cellular receivers may be configured for receiving operating power from a landline telephone jack, and may be also configured for downloading stored cellular messages to the conventional telephone answering device for subsequent replay by the conventional answering device. In this latter embodiment, the cellular receivers may be built as a single unit together with the landline telephone answering device, for example, in a common housing. 
     In still other embodiments of the invention the cellular receivers may be preprogrammed for answering to one or more broadcast numbers. The cellular receivers may be reprogrammable by end users for answering to different or additional broadcast numbers. 
     These and other improvements, features and benefits will be better understood by reference to the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts in schematic form a group of cellsites comprising part of a larger cellular communications network and a number of cellular receivers located in some of the cell areas of coverage provided by the cellsites; and 
         FIG. 2  is a perspective view of a cellular receiver unit according to this invention connected between a wall mounted telephone jack and a typical telephone answering device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  depicts in schematic form a group of cellsites  12  comprising part of a larger cellular communications network  10  and a number of cellular receivers  14  located in some of the cell areas  16  of coverage provided by the cellsites  12 . 
     The cellular communications network  10  and cellsites  12  are configured with hardware and software operative for routing wireless calls and messages to mobile subscribers located within the area of coverage of the network and providing two-way communications with cellular handsets  20  carried by the mobile subscribers. The area of service provided by network  10  is divided into contiguous cells  16 . Coverage for each cell  16  is provided by a group of corresponding cellsites  12 . For example, cellsites  12   a ,  12   b  and  12   c  each include radio transmitters with antennas which have a generally elliptical radiation pattern suggested by ellipses  12 ′ a ,  12 ′ b  and  12 ′ c  respectively, such that these three cellsites together cover the area of one cell  16  contained generally between the cellsites. A conventional cellular communications network  10  is normally configured for monitoring the presence and location of conventional two-way mobile handsets  20  relative to different cellsites  12 , such that messages or calls addressed to mobile numbers assigned to the two-way handsets can be routed by a mobile telecommunications switching office  26  through trunk lines  28  to an appropriate cellsite  12  within radio communications range of the mobile handset  20  corresponding to that mobile number. 
     For purposes of the messaging system of this invention, cellular communications receivers  22  are located within receiving range of the broadcast cellsites  12 . Each receiver  22  is configured to accept calls routed to a broadcast number. However, in the presently preferred embodiment the cellular receivers  22  do not register with the cellular network by identifying themselves to any cellsites  12 , and receivers  22  have no transmit capability at all so that many receivers can operate in one cell  16  without interference or conflict. For purposes of this invention, a subset of mobile numbers, which may be mobile telephone numbers reserved for broadcast use, is reserved for assignment to a special category of subscriber, which is here referred to as a broadcast subscriber. The cellular network  10  is configured through appropriate modification of either hardware, software or both, to make calls to any of the reserved broadcast numbers without testing for the presence of mobile receiving units pertaining to the broadcast numbers. The cellular receivers  22  are each configured to accept calls placed to one or more of the mobile numbers. Multiple broadcast subscribers are assigned different broadcast numbers. Each broadcast subscriber is able to send messages to a group of recipients, each recipient being equipped with a cellular receiver  22  programmed to answer calls placed to that broadcast subscriber&#39;s broadcast number. Different broadcast subscribers can reach different groups of broadcast recipients. 
     Calls placed to a broadcast number from a conventional telephone, either landline or cellular, are transmitted by one or more cellsites  12  without verifying the presence of a mobile handset  20  or receiver  22  corresponding to that broadcast number in the cells  16  covered by those cellsites  12 . When operating in this broadcasting mode the cellsites  12  are referred to as broadcasting cellsites, although physically they may be the same cellsites  12 . The cellsites  12  can operate in both conventional two-way private communication with individual subscribers, or broadcast mode for one-way transmission of messages from one caller to groups of recipients whose identity or presence is not necessarily known or detectable to the cellular network  10 . Consequently, the one-way message broadcasting aspect of the cellular network may coexist with conventional two-way mobile communications on a given network  10 . 
     Multiple such receivers  22  may be configured to accept calls addressed to a same broadcast number by any broadcast cellsite  12 , such that multiple receivers  22  in the same cell  16  may receive a call placed to a single broadcast number. A particular broadcast call or message may be broadcast by multiple cellsites  12  to cover multiple cells  16 , each containing multiple receivers  22  programmed to answer to the same broadcast number, for a wider geographic area of message reception. Also, broadcast calls may be stored by the cellular network system  10  for subsequent broadcast through one or more cellsites  12 , for example, during off-peak times of network usage or to take advantage of momentary frequency availability. 
     The number of cells  16  covered by a cellular broadcast may be determined by the requirements of the broadcast subscriber, for example, as part of a subscription agreement with the cellular network service provider. The broadcasting cellsites  12  may be chosen, for example, to cover a geographic area populated by a given group having a common interest or belonging to a common organization such as a school or church. In such case the broadcast subscriber may be the school or church which is interested in efficiently communicating with its student body or congregants, respectively. In such organizations a large proportion of the group typically resides in general vicinity to the school or church. A cellular message may be delivered to all or most members of the group, when each is equipped with a cellular communications receiver  22 , with a single telephone call placed to the broadcast number assigned to that broadcast subscriber by the cellular network service provider, from any telephone, whether landline or cellular, from anywhere in the world where phone service is available. The number of cellsites accessible by the broadcast subscriber may be a single cellsite for limited local coverage or may include many cellsites if wider area message delivery is needed. 
     In typical cellular communications networks  10  the cellsite  12  sets-up a two-way call or communication session with a mobile handset  20  by assigning available frequencies or channels for the communication session, including a receive frequency and a transmit frequency for the mobile handset  20 . The cellular receivers  22  used in the preferred embodiment of the present invention lack transmission capability, so that no assignment of transmit frequency is needed. However, the receivers  22  may be responsive to communications channel assignment control signals transmitted by the broadcasting cellsites  12 , such that the receiver  22  switches to a receive frequency assigned for the particular broadcast by the broadcasting cellsite  12 , so that the cellular broadcast can be made over a frequency then available to the broadcasting cellsite  12 . This assignment of receive frequencies by the cellsite  12  can be made in the conventional manner currently employed with conventional two way mobile telephone handsets  22 , for example. 
     The cellular receivers preferably have message storage capabilities, such as digital storage, for subsequent replay of received messages. 
     In one embodiment of the invention the cellular receivers  22  are stand alone units with built in message playback capability, including for example, audio playback of voice messages, and for this purpose may have an audio amplifier and loudspeaker as part of the receiver unit. 
     In another embodiment of the invention, illustrated in  FIG. 2 , the cellular receivers  22  is a unit equipped with a cellular antenna  42  and interconnected with a telephone answering device  30  of the type commercially available for answering calls made to landline telephones and storing voice messages for subsequent replay. In the illustrated example, answering device  30  includes a wireless handset  38 . In this embodiment the cellular receivers  22  may be configured for receiving operating power from a landline telephone jack  32 . Receiver  22  has a message storage capability, such as a digital storage, for storing receiver cellular broadcast messages. The receiver  22  is programmed to periodically download the cellular messages initially stored in receiver  22  via cord  40  for storage on answering device  30 , for subsequent replay by the answering device  30 . In such a system, messages received over the telephone land line  34  and the cellular messages received by the cellular receiver  22  may both be replayed in response to the message replay function of the answering device  30 . In a variant of this latter embodiment, the cellular receivers  22  may be built as a single unit together with the landline telephone answering device  30 , for example, in a common housing containing the necessary power supplies for both cellular receiver and answering device. 
     The cellular receiver  22  may be provided with an interface to the conventional answering device  30 . The interface tests for availability of a dial tone from jack  32  to ensure that no landline telephone call is in progress that will be interrupted by offloading of the stored message. The interface may also take the landline telephone line “off-hook” while actuating the answering device  30  and offloading messages from cellular receiver  22 . In  FIG. 2 , the receiver  22  includes appropriate switching for normally connecting answering device  30  to phone jack  32  and bypassing the receiver  22 , and temporarily interrupting this connection for downloading stored cellular messages from receiver  22  to answering device  30 . The answering device  30  need not differentiate between messages conventionally received via the telephone line  34  and messages received via the cellular receiver  22 . Both types of messages are heard in the usual manner by activating the “play messages” function of the recipient&#39;s answering device  30 . In this configuration this system operates with commercially available answering machines  30  of any brand or design without special setup or modification other than the connection of the cellular radio receiver  22  to the answering machine  30 , normally between the recipient&#39;s incoming telephone line  34  and the answering machine  30 , as shown. 
     The cellular receivers  22  may be preprogrammed for answering to one or more broadcast numbers, such that a given cellular receiver  22  may be used to receive messages from various broadcast subscribers representing different organizations of interest to the particular recipient. The cellular receivers  22  may be reprogrammable by end users for answering cellular calls placed to different or additional broadcast numbers, and for this purpose may have a numerical keypad or other suitable input device. 
     In yet another embodiment of the invention, the cellular receivers  22  are modified to include a transmitter section capable of reporting the presence of the receiver to a broadcasting cellsite  12  and registering with the network  10  in a manner similar to the reporting capability of existing two-way mobile telephones. In this embodiment the cellular receivers are registered with the cellular service provider in manner analogous to the registration of two-way mobile telephone handsets, although multiple cellular receivers are still configured to automatically receive calls or messages addressed to a given broadcast number. The broadcasting cellsites  12  in this embodiment can track the cellular receivers present in each cell  16 , for example, for census or billing purposes. 
     In still other embodiments of the invention, a two-way cellular telephone unit such as a mobile handset  20  is modified so as to incorporate the functions of cellular receivers  22  of this invention without prejudice to its normal two-way functionality. For this purpose a separate cellular broadcast receiver  22  subsystem such as described above is included in the housing of the two-way cellular telephone unit  20  and configured to function independently of the two-way subsystem. Alternatively, the cellular receiver section of a two-way cellular telephone unit  22  is modified to also operate in a one-way messaging mode by automatically responding to cellular calls placed to a preprogrammed broadcast number. 
     The cellular telephone network is a convenient means for one-way transmission of messages. However, this invention is not limited to cellular networks and other radio frequency communication networks including simple radio frequency transmitters operating at any convenient frequency can be also employed for message transmission to the multiple receivers  22 . 
     Implementation of the various embodiments disclosed above can be accomplished by those having an ordinary level of skill in cellular communications network engineering or related technologies, based upon the foregoing description without an undue degree of experimentation. 
     Particular embodiments of the invention have been described for purposes of clarity and example. It will be understood, however, that many changes, modifications and substitutions to the described embodiments will be apparent to those having only ordinary skill in the art without thereby departing from the scope of the invention as defined in the following claims.