Abstract:
A user&#39;s access patterns are accounted for in deciding to switch between a plurality of wireless networks  204, 206 . A method according to one embodiment of the present invention includes monitoring a location of a wireless communication device  202  Within a region serviced by a first wireless communication network  204  and second region serviced by a second wireless communication network  206 . The first and second region have an overlapping region which could be serviced by both networks. The future location of the wireless communication device  202  within the first and second regions is predicted based on the monitoring of the previous locations of the wireless communication device  202 . When the wireless communication device  202  is detected as being within the overlapping region, the system determines whether to transfer an active connection between the wireless communication device  202  and one of the networks to the other network. In one embodiment, past patterns of usage of the wireless communication  202  device within the first and second region are identified and used to predict a future location based on the past pattern. In another embodiment, a calender of predetermined time-location associations is input into a controller  203  associated with the wireless communication device  202  and the prediction is based on an actual location and current time being compared with the values input into the calender.

Description:
This is a continuation, of application Ser. No. 08/778,525 filed Jan. 3, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to wireless communication systems and, more particularly, to an improved system and method for controlling hand-offs of calls from one wireless network to another. 
     2. Description of the Related Art 
     During a call connecting a wireless communication device, such as a cellular telephone, with another telephone, the wireless communication device may cross from the domain of one wireless network to an independent wireless network. Such networks may comprise a company&#39;s private cellular telephone network and the public cellular telephone network, for example. Thus, to complete the call, the wireless communication device must be capable of being used in both the company&#39;s internal wireless system and in the public system, and accommodation must be made for controlling hand-offs from one network to the other. 
     Hand-off of a telephone call from the domain of the first wireless network to the domain of the second wireless network may be made via a control link shared between central processing units of the two networks. Using the control link, the two wireless networks are able to negotiate feasibility and operations of hand-off as described, for example, in EIA/TIA interim standard IS42.2-B, “Cellular Radio Telecommunications Intersystem Operations: Intersystem Hand-Off,” which is hereby incorporated by reference. While, ideally, hand-offs from one network to another are imperceptible to the user, in practice, hand-offs frequently introduce extraneous clicks and temporary loss of signal. 
     Frequently a user of the wireless communication device is required to travel from one company site to one or more other company sites, which can cause the wireless communication device to repeatedly switch back and forth between the public and private systems. This can cause unnecessary hand-offs, particularly since typical systems assume that a private wireless system, free of call charges, is preferable to a public system, even though the public systems typically charge a per call access fee. In such systems, a hand-off is always made to the private system, whether or not it is the most efficient in terms of cost or signal quality. 
     This situation is illustrated more clearly with regard to FIG.  1 . In FIG. 1, an exemplary two-network wireless communication system  100  is shown. A private company wireless system is installed in buildings  104 ,  106  and  108 . As illustrated, each building  104 ,  106 ,  108  is associated with its own cell or service area  110   a ,  110   b , and  110   c , respectively. Overlapping the private wireless system is a public wireless system  102  having multiple cells, only two of which,  102   a  and  102   b  ,are shown. 
     As illustrated by the dashed line in FIG. 1, a user can travel from building  104  to building  108 , crossing through cell areas  110   a ,  102   a ,  110   b ,  102 b and  110   c . Assuming that the user begins executing a telephone call in building  104 , the user&#39;s call will be serviced by the private wireless network so long as he is within region  110   a . As soon as the user leaves region  110   a , he will be transferred to the public wireless carrier (so long as he is in region  102   a ). As the user approaches the vicinity of building  106 , he will re-enter into the service area of the private wireless network as represented by cell  110   b . His call will then be transferred back to the private network. As soon as the user leaves the area surrounding building  106 , his call will be transferred from the private network to the public wireless network as he enters region  102   b . Finally, as he approaches building  108 , his call will be transferred back to the private network as enters region  110   c.    
     By the time the user gets to building  108 , he has been transferred four times, each time with a momentary loss of conversation, a change in signal quality and, with every transfer to the public wireless carrier, a new charge per call. Accordingly, a system and apparatus is desired which minimizes the number of unnecessary hand-offs between private and public wireless networks so as to minimize charges and enhance the quality of the call. 
     SUMMARY OF THE INVENTION 
     The above described problems are overcome in large part by a system and method according to the present invention in which a user&#39;s access patterns are accounted for in deciding to switch between the private and public wireless networks. A system and method according to one embodiment of the present invention includes monitoring a location of a wireless communication device within a plurality of regions serviced by a plurality of wireless systems, e.g., a first region serviced by a first wireless communication system and a second region serviced by a second wireless communication system. The first and second regions have an overlapping region which could be serviced by both networks. The system predicts the future location of the wireless communication device within the first and second regions based on the monitoring of the previous locations of the wireless communication device. When the wireless communication device is detected as being within the overlapping region, the system determines whether to transfer an active connection between the wireless communication device and one of the networks to the other network based on the monitoring information. 
     In one embodiment, past patterns of usage of the wireless communication device within the first and second regions are identified and used to predict a future location based on the past pattern. In another embodiment, a calender of predetermined time-location associations is input into a controller associated with the wireless communication device, and the prediction is based on an actual location and current time being compared with the values input into the calender. 
     A method according to another embodiment of the invention comprises compiling a database of time-location associations of a wireless communication device within a first region serviced by a first wireless communication system and a second region serviced by a second wireless communication system. The first region and second regions have a predetermined overlapping region. The method further comprises detecting when the wireless communication device is present within the overlapping region during an active connection and predicting a future location of the wireless communication device within the first region or the second region during the active connection. Finally, the method comprises determining whether to transfer the active connection between the wireless communication device and the first or second wireless communication systems to the other when the wireless communication device is detected as being within the overlapping region. 
     A wireless telecommunication system according to an embodiment of the present invention comprises a first wireless network providing service over a first predetermined region and comprising a first switching office, and a second wireless telephone network providing service over a second predetermined region and comprising a second switching office. The first predetermined region and the second predetermined region overlap in a third predetermined region. A wireless communication device is configured for use in both networks. The second switching office comprises a memory unit configured to store a database of time-location associations related to a presence of the communication device in either the first predetermined region or the second predetermined region. The second switching office also includes a wireless switching control unit coupled to the database, and configured to access the database when the communication device is detected within the third predetermined region and to transfer an active call between the networks based on the time-location associations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention is obtained when the following detailed description is considered in conjunction with the following drawings in which: 
     FIG. 1 is a diagram illustrating an exemplary two network wireless system and the movement of a user therein; 
     FIG. 2 is a block diagram of a wireless network system according to an embodiment of the present invention; 
     FIG. 3 is a more detailed block diagram of a wireless communication device and interface between two wireless networks according to an embodiment of the present invention; 
     FIG. 4 is a flowchart illustrating monitoring of time and location usage patterns; and 
     FIGS. 5-7 are flowcharts illustrating operation of various embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG.  2 —Wireless Network System 
     Turning now to FIG. 2, a diagram illustrating the interaction of a wireless communication device  202 , a stationary telephone  207 , and two wireless systems  204 ,  206  is illustrated. The system and method of the present invention can be used to facilitate the interaction of one or more wireless communication devices  202  and a plurality of wireless systems or networks. In FIGS. 1-7, the present invention is described with reference to private wireless network  204  and public wireless network  206 . As used herein, “wireless communication device” refers to any wireless communication device or wireless telephone, including, for example, pagers, cellular telephones, PCS devices, and other wireless messaging, voice, and data communication devices. 
     The system  200  includes a private wireless network  204  and a public wireless network  206 . Wireless networks  204  and  206  are exemplary of cellular communication device networks or PCS networks of various types. Private wireless network  204  includes a wireless private branch exchange  210  which provides central switching functions to a plurality of cells  210   a ,  210   b , and  210   c . Each cell  210   a ,  210   b , and  210   c  includes an antenna for receiving signals from a wireless communication device and associated equipment, referred to as a base station (not shown), for transmitting the received signals to the wireless private branch exchange  210 . Wireless private branch exchange  210 , in turn, is coupled to a central office  205  representative of, for example, a central office for coupling calls to the public switched telephone network. Wireless private branch exchange  210  further includes a wireless switching control unit  222  configured to record use patterns and store a database relating thereto according to the present invention. Wireless switching control unit  222  includes a processing unit and a memory device to facilitate these functions, as will be described in greater detail below. 
     Public wireless network  206  includes one or more wireless communication device switching offices  208  (MTSO), or PCS switching offices, which provide switching functions to a plurality of cells  212   a  and  212   b . Each MTSO  208  includes a communications controller  209  for supervising communications within and external to the network. Again, each cell  212   a ,  212   b  includes a base station having an antenna for receiving signals from wireless communication devices: and associated equipment for transmitting the signals to the MTSO  208 . MTSO  208  is coupled to central office  205  (which may be a different central office than the one to which the private wireless network  204  is coupled). 
     Wireless communication device  202  is configured for use in either the private wireless network  204  or the public wireless network  206 . Wireless communication device  202  may thus be configured to receive, transmit and process signals according to various frequencies and/or coding standards and/or modulation formats of the varying public and private wireless networks. Exemplary protocols include time division multiple access (TDMA) and code division multiple access (CDMA) protocols. Wireless communication device  202  may also include a smart switching controller  203  configured to perform control operations relating to switching call connections on wireless communication device  202  between private wireless network  204  or public wireless network  206 , as will be discussed in greater detail below. 
     To make a call, the wireless communication device must be registered as a user in the respective network. This is accomplished, for instance, by the communication device and the wireless private branch exchange exchanging control signals. Once the registration occurs, a call from wireless communication device  202  within private wireless network  204  is transmitted to an antenna (not shown) in a cell  210   a ,  210   b ,  210   c  and from the antenna to the wireless private branch exchange  210 . A connection is then made from the wireless private branch exchange  210  to either another wireless private branch exchange or to the central office  205 . From the central office  205 , the connection is made to the public switched telephone network. 
     Similarly, prior to making a call on public cellular network  206 , an exchange of control signals is performed between the wireless communication device  202  and an MTSO  208  of the network. Once this occurs, calls via the public cellular network  206  are made from wireless communication device  202  to an antenna (not shown), within the respective cell, which transmits the signal to the MTSO  208 . The MTSO  208  in turn provides the connection to the central office  205  which connects to the public switched telephone network. 
     As will be discussed in greater detail below, wireless switching control unit  222  is configured to supervise the switching of calls between the two networks based on time-location associations. 
     FIG.  3 —Block Diagram 
     Turning now to FIG. 3, a more detailed block diagram of the wireless systems illustrating various components of one embodiment of the present invention is shown. Components which are common to FIG. 2 retain the same reference numerals. 
     FIG. 3A illustrates wireless communication device  202 . Wireless communication device  202  may include a smart switching control unit (SSC)  203  configured to supervise (in conjunction with the relevant switching exchanges) transfers of active telephone calls from one network to another, based on time-location associations, as will be discussed in greater detail below. Smart switching control unit  203  may comprise a variety of circuits, including microprocessor or micro controllers, or application specific integrated circuits (ASIC). 
     Wireless communication device  202  further includes a wireless private branch exchange communications module (WPCM)  252 , a connection transfer module (CTM)  254 , a PCS communications module (PCM)  256 , and an RF signal strength indicator module  213  (RSSI). Each of the various modules may be comprised in microprocessor or micro controller chips, or in application specific integrated circuits (ASICs). WPCM  252  is used to supervise communications between the telephone  202  and the wireless private branch exchange  210 . PCM  256  is similarly used to supervise communications between the wireless communication device  202  and the MTSO or PCS switch  208 . CTM  254  supervises the switching of calls between cells within a particular network, and between the networks, as will be described in greater detail below. RSSI  213  is used for recognizing the need to make a transfer of a call from, for example, WPBX  210  because of signal fade, which occurs when the caller has gone past a boundary of the region serviced by the private wireless network  204 . 
     Turning now to FIG. 3B, wireless private branch exchange  210  is illustrated. Wireless private branch exchange  210  includes a call management module (CMM)  223 , an RF communications module (RFCM)  225 , and a wireless switching control unit (WSC)  222 . CMM  223  is used for managing the various telephony functions or services associated with the call, such as call transfer, conference call, and the like. RFCM  225  includes an RF transceiver (not shown) and supervises the registration and call set-up of the wireless communication device, as well as the handover or hand-off from one cell to another, and to other networks. WSC  222  is used to supervise the inter-network switching management functions based on time-location associations according to the present invention. More particularly, WSC  222  includes a processor or other control unit  231  and a memory  233  for storing a database of information which is used to predict a user&#39;s patterns of usage. In one embodiment, the database comprises a record of past usages monitored by the processor  231  of the WSC  222 . In another embodiment, the database comprises a user-input calendar of future time-location associations. The processor  231  aboard WSC  222  further monitors the location of the wireless communication device  202  when a call is made or received. The processor  231  accesses the database  233  and predicts a future location of the wireless communication device  202  to determine whether to switch from one network to another. It is noted that, while illustrated as a discrete unit, WSC  222  can be comprised within RFCM, or as a unit external to the WPB 3 X  210 . Thus, FIG. 3 is exemplary only. In addition, it is noted that, while the system preferably operates according to software, hardware implementations are contemplated. 
     A description of the operation of the RSSI  213  is deemed appropriate. When the wireless communication device&#39;s RSSI  213  detects that signal strength has fallen below a predetermined threshold, RSSI  213  communicates with the WPCM  252  to cause the WPCM  252  to attempt to make a handover to another antenna (i.e., within an adjacent cell) having a suitably strong signal. If the WPCM  252  cannot make a handover to an antenna within the private wireless network  204 , it sends a signal to CTM  254 . In response, CTM  254  transmits a signal to PCM  256  to attempt to find another system to which it can transfer the connection. 
     PCM  256  includes controls and apparatus for registering the wireless communication device as a valid user of the public wireless network  206 . “Registration” refers to a method of verifying that the wireless communication device handset can communicate with a wireless network. This is accomplished with respect to public wireless network  206  by the wireless communication device  202  exchanging radio signals with the public wireless network  206  which are designed to establish status as a valid user. The exchange of radio signals takes place in accordance with protocols which are well known to those of skill in the art, for example, according to EIA/TIA interim standard “IS-54B Cellular System Dual Mode Mobile Station—Base Station Compatibility Standard.” If the registration is successful, PCM  256  sends a signal indicating that condition to CTM  254 . CTM  254  in turn provides the connection (i.e., transfers the call between the networks). 
     According to the present invention, call transfers are made based on the time-location associations independent of the signal strength determination. Call transfers based on the time-location associations are similar to call transfers based on the signal strength determination. When the wireless communication device  202  enters within range of both networks, and a call is in progress, the processor  231  of the WSC  222  identifies whether the user will be repeatedly entering and exiting the region serviced by, for example, the private wireless network. This identification occurs through the processor  231  of the WSC  222  accessing a database in memory  233  in which user time-location associations are stored. In one embodiment, the time-location associations comprise a record based on the processor  231  monitoring the past usage of the wireless communication device  202 . The locations can comprise, for example, the individual cells of the network. Time associations can be either based on duration within the cell and time-of-day associations, where applicable. In another embodiment, the database time-location associations comprise a calendar manually input by the user of his or her predicted schedule. In still another embodiment, the database comprises a combination of a user-input calendar and the monitored record. 
     Assume, for example, that a call is in progress on the public cellular network  206 , and the user enters a region serviced by the private network  204 . The WPBX  222  learns of the presence of the wireless communication device, for example, via a signal from the wireless communication device  202 , i.e., from the exchange of control signals described above. If, after accessing the database in memory  233 , the processor  231  of WSC  222  determines that the user will not, in fact, be repeatedly entering and exiting the region serviced by the private network, the WSC  222  signals the SSC  203  of the wireless communication device  202 . The wireless communication device  202  allows the CTM  254  to effectuate a transfer from the public wireless network to the private wireless network. The PCM  256  informs the MTSO  208  of the public network  206  to release the call, and it is switched to the private network  204 . It is noted that while supervision of this functionality on the wireless communication device end has been described with regard to the SSC  203 , this functionality may be incorporated into the various other modules of the wireless communication device. It is similarly noted that while RSSI  213  and SSC  203  are illustrated as discrete units, in alternative embodiments, they may be integrated into a single unit. If the processor  231  of the WSC  222  determines that the user will be repeatedly entering and exiting the region serviced by the private network, the WSC  222  either does nothing, or provides a control signal indicating that the wireless communication device is to continue being serviced by the public wireless network. 
     In another embodiment, the time-location associations comprise a record of cells and transit patterns relating to durations of time required to cross through the cells. The stored transit patterns may result from monitoring past usages, as described above, or a calendar input by the user, again, as described above. Thus, if a user has an active connection in the public network, and enters and remains within a cell of the private network for longer than a predetermined period, the system will switch to the private network. If the user stays within the cell for less than the predetermined period, however, the connection will remain with the public network. 
     For example, if the user has an active connection on the public network, his or her entry into a cell serviced by the private network will be detected, such as by the above-described registration process. The processor  231  accesses the database of time-location associations, which include a record of how long it takes to transit through the cell. If the user remains within the cell for longer than the determined period, the call connection will be transferred, as described above. 
     FIG.  4 —Flowchart of One Embodiment of Processor Monitoring 
     Turning now to FIG. 4, a flowchart illustrating the monitoring operation according to one embodiment of the invention is shown. Initially, a call involving wireless communication device  202  is detected (Step  450 ) and processed, for example, by the wireless private branch exchange  210 . The call may be either a received call or one initiated by the wireless communication device  202 . As discussed above, call processing includes the exchange of various control signals between the telephone&#39;s WPCM  252  and the wireless private branch exchange&#39;s CMM  223  and RFCM  225 . 
     The processor  231  detects the servicing of the call and determines the time of the call (Step  452 ). In addition, the processor  231  determines the location of the wireless communication device  202  (Step  454 ) at the time of servicing the call. This may comprise, for example, the processor  231  monitoring present cell location and cell switching operations as controlled from the wireless private branch exchange. Alternatively, SSC  203  may provide control time-location information directly to the wireless private branch exchange. The processor  231  then stores the times and locations in memory  233 , and later compiles it into a usable database (Step  456 ). It is noted that, in one embodiment, the monitoring of the wireless communication device&#39;s (and hence user&#39;s) location, may be disabled. It is similarly noted that, in an alternate embodiment, constant monitoring of the wireless communication device&#39;s location (even when there is no active call), for example, by the SSC  203  (or other functional modules of the wireless communication device) registering within each cell, or providing information within a global positioning system (GPS), is contemplated. Finally, the monitoring of the usage patterns may further comprise monitoring the duration of time the user spends within a cell. 
     FIG.  5 —Flowchart of Operation of One Embodiment of the Present Invention 
     Turning now to FIG. 5, a flowchart illustrating operation of an embodiment of the present invention is shown. Time-location associations of the wireless communication device are stored and compiled by the processor  231  as a database in the memory device  233  coupled to or within WSC  222  (step  302 ). For example, the location of the wireless communication device within the public network or the private network may be monitored by the processor  231  over time. The usage patterns of the wireless communication device (i.e., whether the wireless communication device is activated and registered as a user in a particular cell of one or the other of the networks) are monitored. Alternatively, and to provide a more accurate record of the user&#39;s actual schedule, so long as the wireless communication device is ON, the SSC  203  may be configured to provide a signal to the WSC  222  identifying the user&#39;s location within particular cells. The usage patterns may further comprise a record of the user&#39;s duration of time within a particular cell (i.e., how long it takes the user to transit through a cell). 
     Next, when the user initiates an active connection on the wireless communication device, the system detects the location of the device making the call (step  304 ). In addition to being used to manage the call, this information is used in order to determine whether the device&#39;s presence within a region serviced by the private network or the public network is transitory (i.e., whether the user will be repeatedly entering and re-entering one or the other of the networks). The processor  231  in the WSC  222  accesses its database and predicts what the user&#39;s usage is likely to be (Step  306 ). As noted above, this may comprise determining how long it should take for the user to transit through the particular cell. 
     Based on the present time and user location, and the result of the accessed time-location associations from the database, the processor  231  determines whether to transfer the call (Step  308 ). This may comprise, for example, the processor  231  waiting a predetermined period for the user to transit a cell. Finally, if the processor  231  determines that a transfer is necessary, the appropriate control signals are issued which effectuate the transfer from the one network to another (Step  310 ). For example, if the call is presently being serviced by the public network, and a determination is made to transfer the call, the WSC  222  sends a signal to the WPCM  252  (for example), which in turn, signals the CTM  254  to initiate a transfer from the public network  206 . 
     It is noted that the system preferably continually updates the database. Thus, a user&#39;s usage patterns that are inconsistent with the previously stored and compiled database record are periodically incorporated into an updated database, to more optimally predict a future location. 
     FIG.  6 —Flowchart of Alternate Embodiment 
     Turning now to FIG. 6, a flowchart illustrating operation of an alternate embodiment of the present invention is shown. In the illustrated embodiment, rather than monitoring past usage patterns, the system allows the user to input his schedule, according to time and location (Step  350 ). This may further comprise the user entering estimates of his or her transit times through particular cells. Thus, the user determines what his schedule is likely to be during, for example, the coming week. He or she then records this information, for example, on a computer diskette, and uploads the information to the WPBX  210 . Alternatively, provision may be made for the user to input this information directly from the wireless communication device  202 . The WSC  222  stores the information within the memory  233  and compiles a database. 
     Once the database has been compiled, the system is ready for use. Next, when the user initiates an active connection on the wireless communication device, the system (preferably processor  231 ) detects the location of the device making the call (step  352 ). In addition to being used to manage the call, this information is used in order to determine whether the device&#39;s presence within a region serviced by the private network or the public network is transitory (i.e., whether the user will be repeatedly entering and re-entering a region serviced by one or the other of the networks). The processor  231  of WSC  222  accesses its memory  233  for the database (Step  354 ) and determines whether to transfer the call, by predicting what the user&#39;s future usage pattern is likely to be (Step  356 ). This may comprise waiting a predetermined period for the user to exit the cell. Finally, depending upon the outcome if the determination in Step  356 , the call is transferred (Step  356 ). 
     For example, if the call is presently being serviced by the public network, and a determination is made to transfer the call, the WSC  222  sends a signal to the WPCM  252  (for example), which in turn, signals the CTM  254  to initiate a transfer from the public network  206 . It is noted that the calendar operation described with regard to this embodiment may also be incorporated into the embodiment described above with respect to FIG.  5 . Thus, for example, both the user&#39;s schedule and his actual access patterns may be used to determine whether a call should be transferred from one network to the other. 
     FIG.  7 —Flowchart of Exemplary Operation of Present Invention 
     Turning now to FIG. 7, a flowchart  400  illustrating an exemplary operation of the present invention is shown. Flowchart  400  illustrates the call processing procedure for a user traveling as illustrated in FIG.  1 . For example, the user initiates a call within building  104  serviced by cell  110   a  of the private wireless network  204 . The call is routed to the wireless private branch exchange  210  connected to a central office  205  of the public switched telephone network (step  402 ). As illustrated by the dashed line, the user exits building  104  and leaves the area  110   a  serviced by the private wireless network  204  (step  404 ). The RSSI  213  detects a signal fade and requests a transfer to the public wireless network  206 . The connection to the public network is executed as described above (step  406 ). The user continues on and enters cell  110   b  (near building  106 ), which is serviced by both the public network  206  and the private network  204 . Upon the user&#39;s entry into the area  110   b , the system determines whether or not the user&#39;s presence within the area  11  Ob is relatively permanent (i.e., whether the user is likely to be remaining within the building for longer than a predetermined period) (step  410 ). As described above, this determination is based on the WSC  222  accessing its database and providing appropriate controls signals responsive thereto. 
     If the user&#39;s presence is only transitory, the system will continue the call via the MTSO of the public network (step  412 ). If the user&#39;s presence within area  110   b  is determined to be relatively permanent, however, the call will be transferred to the private network to be serviced through the wireless private branch exchange  210  (step  416 ). If the user then leaves building  106  and enters the area serviced by cell  102   b  of the public network (step  418 ), the call will be transferred to the MTSO  208  of the public network (step  422 ). 
     If, in step  412 , the user continues into cell  102   b , serviced by the public wireless network (step  420 ), the call continues to be serviced by the public network (step  424 ). The user in either case continues on into area  110   c , serviced by the private wireless network (step  426 ). Again, a determination is made whether or not the user&#39;s presence is relatively permanent or transitory (step  428 ). If the user&#39;s presence is determined to be only transitory (i.e., less than a predetermined period), then the call continues to be processed by the public wireless network (step  430 ). If, however, the user&#39;s presence is determined to be relatively permanent, then the call is processed by the private network (step  432 ). 
     The invention described in the above detailed description is not intended to be limited to the specific form set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as can reasonably be included within the spirit and scope of the appended claims. For example, while illustrated with respect to a private wireless network and a public wireless network, the invention is equally applicable to more than one public network.