Abstract:
A system and method that tests emergency services location information and provides virtually instantaneous feed-back to a technician in the field, monitoring center or both. A location of a mobile communications device is determined by the technician via independent means and a call is placed to a special test number. When an element in the mobile network receives the call, it recognizes the special number and obtains location information regarding the mobile communications device by the means currently employed in the art for emergency services calls. The location information is delivered back to the calling mobile communications device, where it is compared to the previously-determined location. The two locations may then be stored on the mobile communications device, forwarded to a monitoring center or both.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to verification of communications network-derived location information, and, more specifically, to a system and method that tests network-derived location information regarding a mobile communications device (such as a wireless communications device, Voice over Internet Protocol (VoIP) communications device, etc.) relative to the actual location of the mobile communications device for location-based services. This invention is particularly relevant to testing network-derived emergency services (i.e., 9-1-1) location information regarding a mobile communications device. 
     When abbreviated emergency services dialing (“9-1-1” in the U.S. and Canada) was first introduced, the emergency services operator had to ask the caller for a call-back telephone number and the location that the caller was calling from, among other information regarding the nature of the emergency. If the caller was unable to communicate this basic information to the operator, (because, for example, the caller was injured or did not speak the language), then help could not be dispatched. 
     To alleviate this problem, enhanced 9-1-1 (E9-1-1) was developed. In E9-1-1, the telephone number of the calling telephone is delivered with the call to the local public safety answering point (PSAP). The PSAP queries a regional Automatic Location Information (ALI) database using the calling telephone number as a key. The ALI database returns a record containing the street address and, in some cases, other information associated with the calling telephone number. The operator at the PSAP that takes the call is then presented with the calling telephone number and the street address associated with the calling telephone number. Such information aids the operator to call the telephone back in case the call is cut off for any reason and aids the operator in guiding help to the location of the caller. 
     To provide E9-1-1 capabilities for landline telephone subscriber in the current art, the physical address of the subscriber and the call-back number of the telephone are manually provisioned in the appropriate ALI database. In most cases, the incumbent local exchange carrier (ILEC) or competitive local exchange carrier (CLEC) track all landline telephone number changes and either report them to a clearing house that maintains the ALI database or updates the appropriate ALI database themselves. 
     The above-described system works very well in landline-based telephony, because telephone number and address are relatively fixed, changes occur slowly over time and changes occur in a manner easily tracked by the ILEC&#39;s or CLEC&#39;s. Wireless communications devices, however, do not have a fixed location by definition. Various governmental mandates now require that, when a wireless communications device makes an emergency services (e.g., 9-1-1) call, the wireless communications service provider must deliver the calling number (for call-back purposes) and at least a general location. In the United States, the government mandate requires implementation in two phases. Phase I implementation requires that the wireless communications network identify the cell site, cell sector, or both, that are handling the call. For phase II, The street address and, preferably, the actual location (i.e., the latitude and longitude, also called herein “X/Y coordinates”) of the calling wireless communications device must be delivered. 
     VoIP telephony is another communications technology that is not compatible with the above-described landline emergency services paradigm. VoIP communications devices may be plugged into a data network at a first location one day and then plugged in at a second location the next. Furthermore, some VoIP communications devices are wireless, that is; these VoIP communications devices connect to a data network at an access point via radio signals. The United States Government mandates that the location (again, at minimum street address and optionally latitude and longitude) of VoIP communications devices also be delivered. Wireless and VoIP communications devices are referred to herein as “mobile communications devices.” 
     Additionally, the United States government requires that wireless communications service providers periodically test the location system to verify that the location of a calling mobile communications device is being accurately determined and is in compliance with 9-1-1 emergency call mandates. Such verification currently involves one or more field technicians making a plurality of calls to a special number and recording the location from which the call was made using an independent location reference device (such as a global positioning system device). The location of the calling mobile communications device is determined and recorded by the communications network. The technician and/or other service personnel then manually compare the two lists and determine whether accurate location information is being determined. However, the location of the mobile communications device derived by the communications network is not readily available to the technician until sometime later, when the technician has access to the locations recorded by the communications network. 
     A problem in the art is that the current manual method of testing location information is time intensive and therefore costly. Additionally, if any errors occur when the wireless communications system determines the location of the wireless communications device, these errors cannot be detected until later and result in repeated testing. 
     SUMMARY OF THE INVENTION 
     This problem is solved and a technical advance is achieved in the art by a method that provides virtually instantaneous feedback to a technician in the field, technician monitoring testing or both. In accordance with one aspect of this invention, a location of a mobile communications device is determined by independent means, such as a global positioning system (GPS) device or a map (which may include identifications of cell sites that serve locations on the map). A call is placed to a special number, which is preferably not an emergency services number (i.e., not 9-1-1). When a mobile switching center (MSC) receives the call, it recognizes the special number and obtains location information from a positioning center (e.g., a mobile positioning center (MPC) or a gateway mobile location center (GMLC)), regarding the wireless communications device by the means currently employed by the MSC for emergency services calls. The location information may comprise the cell site ID, the sector of the cell site, the X/Y coordinates of the calling communications device, the serving public safety answering point (PSAP) ID, or some combination thereof. The location information is delivered back to the calling mobile communications device, where it is compared to the previously-determined location. 
     Advantageously, such communication is effected using one or more short message service (SMS) messages sent to the technician&#39;s mobile communications device. The two locations may then be stored on the wireless communications device, forwarded to a monitoring center, stored in a separate storage system (e.g., a laptop computer, a personal digital assistant, etc.) or any combination thereof. In accordance with one aspect of this invention, the mobile communications device comprises a wireless communications device (e.g., a “cell phone,” a wireless laptop, etc.). In accordance with another aspect of this invention, the mobile communications device comprises a VoIP communications device (e.g., a VoIP telephone, a dual-mode cell phone, etc.). 
     According to another aspect of this invention, once the positioning center determines the location of the wireless communications device, the location is forwarded to a monitoring center. The location of the mobile device is also forwarded to the monitoring center by the field technician. The monitoring center may comprise a test results database accessible by the field technician. Advantageously, the monitoring center may comprise a web site accessible by the technician in the field via, for example, the wireless communications device, a laptop, or any device with data communications capability. In this manner, the location of a wireless communications device as determined in accordance with emergency services procedures may be compared to the actual location is real or near-real time. Adjustments may then be made in order to increase the accuracy of the emergency services procedures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of this invention may be obtained from a consideration of this specification taken in conjunction with the drawings, in which: 
         FIG. 1  is a block diagram of a wireless communications network in which a first embodiment of the present invention operates; 
         FIG. 2  is a call flow diagram of an emergency services call in accordance with the prior art in the context of  FIG. 1 ; 
         FIG. 3  is a call flow diagram of a special number test call in the context of  FIG. 1 ; 
         FIG. 4  is a block diagram of a communications network in accordance with a further embodiment of the present invention; 
         FIG. 5  is a call flow diagram of a special number test call in the context of  FIG. 4 ; 
         FIG. 6  is a block diagram of a communications network in accordance with another further embodiment of this invention; and 
         FIG. 7  is a call flow diagram of a special number test call in the context of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a wireless communications network  100  in which a first exemplary embodiment of this invention operates. Wireless communications network  100  comprises a network operating in accordance with GSM standards as is known in the art. Thus, wireless communications network  100  comprises a plurality of cell sites, represented by cell sites  102 ,  104  and  106 . The plurality of cell sites is connected to a plurality of base station controllers, represented by base station controller (BSC)  108 . All BSC&#39;s, including BSC  108 , are connected to a GSM mobile switching center (MSC)  110 . Cell sites  102 ,  104  and  106 , BSC  108  and MSC  110  are well known in the art and are thus not further described. MSC  110  is connected to a selective router  112  that routes the call to a public safety answering point (PSAP)  124 , which are also known in the art and thus not further described. 
     While this invention is described in terms of a GSM-based wireless communications network, one skilled in the art will understand how to implement this invention in wireless communications networks based on other standards (such as a CDMA network) after studying this specification. 
     In order to understand the importance of this invention, handling of a special number call by wireless communications network  100  according to the prior art is now described in the context of the call flow of  FIG. 2 . Each step in the call flow of  FIG. 2  is indicated in parenthesis after the description of that step in  FIG. 1 . 
     The user of mobile communications device  114  enters an emergency services number and presses send. For purposes of describing this invention, the emergency services number is 9-1-1, the North American emergency services number. Mobile unit  114  sends a call origination message, including the dialed number (9-1-1) and the identity of mobile unit  114  to a serving cell site, which, in this exemplary embodiment, is cell site  106 , over a radio interface, represented by communications channel  116 . ( 202 ) The identity of a mobile unit is usually the mobile subscriber integrated services digital network number (MSISDN), but may also be the international mobile subscriber identity (IMSI) or the mobile directory number (MDN). For purposes of describing this invention, MSISDN is used to indicate MSISDN, MDN, IMSI or any other indicia that uniquely identifies the mobile unit to the wireless communications network. 
     Cell site  106  forwards the call to BSC  108 , including the dialed number and the MSISDN. ( 204 ) BSC  108  forwards the call with the dialed number, the MSISDN and the serving cell site ID to MSC  110 . ( 206 ) MSC  110  recognizes the emergency services number (the dialed number) and initiates its location determination procedure. To this end, MSC  110  sends a query to gateway mobile location center (GMLC)  118  to determine how to route the call, passing it the MSISDN and an identification of serving cell site  106 . ( 208 ) In accordance with Phase I wireless emergency services, GMLC  118  applies the identification of serving cell site  106  to a table and selects a serving public safety answering point (PSAP)  124  that serves the location proximal to the cell site. Processing skips steps  210 ,  212 ,  214 ,  216 ,  218 , and  220  (which are shown in  FIG. 2  in phantom for that reason) and proceeds directly to step  222  (described below). 
     In accordance with Phase II wireless emergency services, GMLC  118  sends the MSISDN and the cell site identification to serving mobile location center (SMLC)  120  via MSC  110 . ( 210 ,  212 ) SMLC  120  determines the X and Y coordinates of calling mobile unit  114  and returns the X/Y coordinates back to GMLC  118  via MSC  110 . ( 214 ,  216 ) GMLC  118  applies the X/Y coordinates to a coordinate routing database (CRDB)  122 . ( 218 ) CRDB  122  comprises at least a mapping of geographical locations served by wireless communications system  100  to a serving public safety answering point (PSAP). 
     In this exemplary embodiment, PSAP  124  serves the location around cell site  106 . GMLC  118  receives a PSAP ID from CRDB  122 . ( 220 ) GMLC determines an emergency services routing key (ESRK) and delivers the ESRK to MSC  110 . ( 222 ) MSC  110  delivers the call to selective router  112  with 9-1-1 as the called number and the ESRK as the calling number. ( 224 ) Selective router  112  uses the ESRK select a PSAP from the plurality of PSAP&#39;s to which it is connected, which, in this exemplary embodiment is PSAP  124 , and delivers the call to PSAP  124  passing the ESRK as the calling number. ( 226 ) 
     PSAP  124  queries automatic location information (ALI) database  126  using the ESRK as a key. ( 228 ) ALI  126  recognizes the ESRK as a special number requiring further information and queries GMLC  118  with the ESRK. ( 230 ) GMLC  118  delivers the location information and the MSISDN of mobile unit  114  back to ALI  126  ( 232 ), which, in turn, delivers the location information and MSISDN to PSAP  124 . ( 234 ) 
     From the above description, it is clear that a system to test the accuracy of GMLC  118 , SMLC  120  and CRDB  122  is required so that emergency services calls do not have to be rerouted from one PSAP to another if a determination is made by a PSAP operator that mobile communications device  114  is actually in a location served by another PSAP. As described above, the prior art method for testing is for mobile communications device  114  to place a call to a test number. MSC  110  recognizes the test number and performs the above-described steps  208 - 216  or  222 . GMLC  118  stores the test results in test results database  130 . The call is completed to some predetermined destination in the public switched telephone network (PSTN)  132  or the call is terminated. The technician using mobile communications device  114  logs the time and the location from which the call was made. The technician&#39;s log is then manually compared to the records in test results database  130  and any discrepancies are noted. 
     In accordance with this invention, and in contradistinction to the prior art, the test results are delivered to the technician in the field as the test is in progress. In this manner, discrepancies are more quickly and easily determined and corrected; thus saving time and, in the case of 9-1-1 routing, improving emergency services. 
     Such beneficial results are achieved by GMLC  118  sending a short message service (SMS) message containing the test results (that is, X/Y coordinates) via short message service center (SMSC)  150  back to mobile communications device  114 , either instead of recording the results in test results database  130  or supplemental thereto. An exemplary embodiment of this invention is now described in the call flow of  FIG. 3  taken in the context of  FIG. 1 . Call flow steps from  FIG. 3  appear in parenthesis after the step described. 
     The technician determines his or her current location using a location determining device, such as, but not limited to, a global positioning system (GPS) device, a map of the area being tested (which may include the location of cell sites  102 ,  104  and  106 ) or both. Such location determination may take place before, during or after making the test call. Location determining device  154  may comprise a stand-alone device, may be incorporated into mobile communications device  114  or may advantageously be a combination device, such as a laptop computer, that can make wireless calls, determine location and record results. Advantageously, mobile communications device  114 , location determining device  154 , or both, are SMS-enabled devices. 
     In accordance with this embodiment of this invention, the technician using mobile communications device  114  makes an emergency services test call by entering the emergency services test number, such as 9-2-2, and sending a call setup signal to the serving cell site, which in this exemplary embodiment is cell site  106 . Mobile communications device  114  delivers it MSISDN to cell site  106 . ( 302 ) An emergency services test number that is not the same as the emergency service number is preferred so that the test call does not use valuable emergency services resources. Cell site  106  forwards the call to BSC  108 , delivering the dialed number (9-2-2) and an identification of mobile communications device  114 , which generally comprises the MSISDN of the device. ( 304 ) 
     BSC  108  forwards the call to MSC  110 , passing the dialed number, MSISDN, cell site ID and, optionally, the sector of the cell site. ( 306 ) MSC  110  recognizes the emergency services test number and sends an outgoing ISUP IAM or an SLR message (an ESRK request) to GMLC  118 . The outgoing message includes the MSISDN of mobile communications device  114 . ( 308 ) If wireless communications network  100  is operating in a phase I mode, steps  310 ,  312 ,  314 ,  316 ,  318  and  320  are skipped and processing continues directly to step  324 . GMLC  118  applies the identification of serving cell site  106  and, optionally, the sector to a table and selects a serving public safety answering point (PSAP)  124  that serves the location proximal to the cell site. 
     If wireless communications network  100  is operating in phase II mode, GMLC  118  delivers a PSL message to MSC  110 , passing the MSISDN and cell ID ( 310 ), which MSC  110  forwards to SMLC  120 . ( 312 ) SMLC  120  determines the X/Y coordinates of mobile communications device  114  and returns the derived X/Y coordinates to MSC  110 . ( 314 ) MSC  110  forwards the X/Y coordinates to GMLC  118 . ( 316 ) 
     GMLC  118  queries CRDB  122  with the X/Y coordinates. ( 318 ) CRDB  122  returns a PSAP ID to GMLC  118 . ( 320 ) GMLC  118  selects a non-PSAP telephone number (such as time and temperature or weather) and returns it to MSC  110 . ( 322 ) MSC  110  completes a call path to the destination telephone number. ( 324 ) In accordance with this invention and in contradistinction to the prior art, GMLC  118  sends a SMS message, which includes the MSISDN, Cell ID, X/Y coordinates, PSAP ID, or any combination thereof. ( 326 ) 
     MSC  110  sends the SMS message to SMSC  150 . ( 328 ) SMSC  150  locates mobile communications device  114  in the manner known in the art, and send the short message back to MSC  110 . ( 330 ) MSC  110  handles this message as it would any short message, and delivers the message to BSC  108  ( 332 ), which forwards it to cell site  106 . ( 334 ) Cell site  106  delivers the short message to mobile communications device  114 . ( 336 ) 
     At this point, the technician has both the location as personally determined and the location as determined by wireless communications network  100 . In this manner, the technician has sufficient location information to determine whether wireless communications network  100  adequately determines the location at which the technician is currently located. 
     In accordance with this invention, therefore, the technician has at least the cell site ID (for phase I systems), which can be compared to a cell site map, other information that the technician has regarding local cell sites and cell site coverage, or both. Preferably, the technician also has the network-determined X/Y coordinates and can compare these to the technician&#39;s independent location determination. In addition, the technician may have a PSAP ID that can be compared to an emergency services zone map to determine whether the identified PSAP actually serves the emergency services zone in which the technician made the test call. Thus, this exemplary embodiment provides a technician with more information more quickly than the prior art, which aids wireless communications service provider in providing accurate emergency services. 
     In the above-described exemplary embodiment, GMLC  118  sends an SMS message to SMS server  150  in steps  326  and  328 . This embodiment advantageously uses the SMS message system with only minor modifications to GMLC  118 . In an alternative exemplary embodiment, GMLC  118  may format and send an SMS message directly back to mobile communications device  114 . While this alternative exemplary embodiment requires more modifications to GMLC  118 , it provides information back to mobile communications device more rapidly and thus may be more desirable when, for example, the mobile communications device is moving. 
     Further, the above-described exemplary embodiment is described in terms of a call being made from mobile communications device  114  and receiving an SMS message in return. One skilled in the art will realize that an SMS message may be used to initiate location testing. In this exemplary embodiment, the technician enters an SMS test message and sends the message to a test number. The MSC  110  recognizes the test number and performs location determination as described above. Optionally MSC  110  forwards the SMS test message to another system, such as GMLC  118 , to process the message and perform location determination. The location is then returned back to the technician in another SMS message. In this exemplary embodiment, no voice path resources are used, providing an additional savings in network resources. 
     Turning now to  FIG. 4 , another exemplary embodiment of this invention is shown in the context of communications network  400 . The communications network  400  is similar to the communications network  100  of  FIG. 1 . In accordance with this embodiment of this invention, however, GMLC  118  is connected to a data network  402 . A web page server  404  is also connected to data network  402 . Data network  402  may be a public data network, such as the Internet, may be a private data network or may be a signaling network, such as signaling network  152  ( FIG. 1 ). 
     An emergency services location test call is now described in the context of  FIG. 4  taken in conjunction with the call flow of  FIG. 5 . In this exemplary embodiment, the technician makes an emergency services location test call on mobile communications device  114  by entering the emergency services test call number, such as 9-2-2, and sending a call setup signal to cell site  106 , which includes its MSISDN. ( 502 ) Cell site  106  forwards the call through BSC  108  ( 504 ) to MSC  110 , which delivers the dialed number (9-2-2), the cell site ID of cell site  106  and the MSISDN of mobile communications device  114 . ( 506 ) 
     MSC  110  recognizes the emergency services test number and delivers the MSISDN and cell ID to GMLC  118 . ( 508 ) Again, if wireless communications network  400  is a phase I network, processing skips steps  510 ,  512 ,  514 ,  516 ,  518  and  520  and proceeds directly to step  522 . If wireless communications network  400  is a phase II network, GMLC  118  sends the MSISDN and cell ID to MSC ( 510 ) for delivery to SMLC  120  ( 512 ). SMLC  120  performs location determination of mobile communications device  114  and delivers X/Y coordinates for the MDN back to MSC  110  ( 514 ), which forwards them to GMLC  118 . ( 516 ) GMLC  118  applies the identification of serving cell site  106  to a table and selects a serving public safety answering point (PSAP)  124  that serves the location proximal to the cell site. 
     When GMLC  118  has the X/Y coordinates, it assigns a test TN. In accordance with this exemplary embodiment, GMLC  118  forwards the MSISDN, cell ID, X/Y coordinates, PSAP ID or any combination thereof to web server  404  over data network  402 . ( 524 ) Advantageously, MSC  110  delivers the call to the test TN (a non-PSAP location, such as time and temperature). ( 526 ) The technician can then manually or automatically up load the location information to web page server  404  determined in situ in any manner known in the art. 
     Turning now to  FIG. 6 , another alternative embodiment of this invention is shown, in the context of communications network  600 . Communications network  600  comprises a VoIP communication network in this exemplary embodiment. As such, there are a plurality of access points, represented by access point  602 , access point  604  and access point  606 . All access points  602 ,  604  and  606  are connected, either directly or indirectly, to a call server  610 . For purposes of clarity in this figure, access points  602 ,  604  and  606  are shown directly connected to call server  610 . One skilled in the art will understand that there may be one or more data networks between and among access points  602 ,  604  and  606  and call server  610 . 
     For purposes of describing this exemplary embodiment, VoIP mobile communications device  614  is in radio communications  616  with access point  606 , via, for example, Wi-Fi. Call server  610  routes emergency services calls by querying VoIP positioning center (VPC)  618 , which queries location information center (LIS)  620 , as will be described further, below, in order to locate a calling VoIP mobile communications device, such as VoIP mobile communications device  614  and route the call to a serving PSAP. Call server  610  is connected directly or indirectly to one or more selective routers, represented by selective router  112 , which connects emergency services calls to one or more PSAP&#39;s, represented by PSAP  124 . PSAP  124  queries ALI  126  for location information, which, in turn, obtains location information from VPC  618 . 
     An emergency services location test call is now described in the context of  FIG. 6  taken in conjunction with the call flow of  FIG. 7 . As described above, the technician makes an independent determination of location before, during or after making the test call. In this exemplary embodiment, the technician makes an emergency services location test call on VoIP mobile communications device  614  by entering the emergency services test call number (again, preferably not 9-1-1) and sending a call setup signal including its telephone number (TN) to access point  606 . ( 702 ) Access point  606  forwards the call to call server  610  and includes the TN and its access point identification (APID). ( 704 ) 
     Call server  610  recognizes the emergency services test call number and forwards the TN and APID to VPC  618 . ( 706 ) VPC  618  determines that a location of the access point is needed, and forwards the TN and APID to LIS  620 . ( 708 ) LIS  620  determines the X/Y coordinates of access point  606  and returns them to VPC  618 . ( 710 ) VPC  618  queries CRDB  122  with the X/Y coordinates ( 712 ), which returns a PSAP identification. ( 714 ) 
     Because this is a test call, VPC  618  delivers a test TN to call server  610 . ( 716 ) Call server  610  causes the call to be completed between VoIP mobile communications device  614  and the test TN. ( 718 ) VPC  618  then delivers the TN, APID, X/Y coordinates, PSAP ID, or an combination thereof back to VoIP mobile communications device  614 . ( 720 ) The technician now has sufficient information to determine the accuracy of communications network  600  ability to located VoIP mobile communications device  614 . 
     While this embodiment is described in terms of wireless VoIP, one skilled in the art will understand how to modify this embodiment to wired network VoIP after studying this specification. 
     It is to be understood that the above-described embodiment is merely illustrative of the principles of the present invention and that many variations of the above-described embodiments can be devised by one skilled in the art without departing from the scope of the above-described invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.