MXPA98005833A - Routing of a celu telephone emergency call - Google Patents

Abstract

A cellular telephone network (10) including a plurality of service areas (26), each served by a different mobile switching center (12) where messages are transmitted between the mobile switching centers, taking into account cases of fading area between mobile subscriber cellular call service, to identify the public security answering point (PSAP) system (24) to be used when answering an emergency telephone call from the mobile subscriber. When multiple area fades have occurred between multiple services, the PSAP identification message (32) is sent from the center (12 (2)) of mobile service switching or (12 (3)) to the center (12 (1)) of mobile anchor switching to allow identification of the appropriate PSAP. This message could be retransmitted through one or more centers (12 (2)) of intermediate tandem mobile switching

Description

ROUTING A CELL PHONE EMERGENCY CALL BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates to non-cellular telephone networks and, in particular, to the routing of calls - emergency telephones through a cellular telephone network. Description of the Related Technique In an emergency situation, it is vitally important for emergency service providers, such as -the fire, police and rescue departments, to have access to location information regarding the emergency site of -mode that emergency personnel and equipment can be dispatched -properly and on time, in some cases, however, the nature of the emergency makes it difficult, if not impossible, to give the person reporting the emergency situation, provide the necessary location information to the site of the - emergency. For example, the person reporting the emergency - may be incapacitated or otherwise unable to orally report their location to emergency services personnel. Emergency service providers have been greatly helped in their efforts to provide emergency services to individuals in need through the introduction of 911 emergency dialing services through the telephone network. An important aspect of the 911 emergency service is that the public safety answering system (PSAP) used to answer the emergency telephone call obtains from the telephone system the telephone number of the telephone from which the emergency is being reported. Using this telephone number, the PSAP system has access to a database containing information related to the telephone numbers to the names and addresses of the customers of -phones, and withdraws the name and billing address of the telephone customer who has the telephone number. telephone number from which the emergency call was initiated. Other information, such as a home address if different from the billing address and special medical information, is also available from the database. For an emergency call originated from a landline telephone 'that is, a land line with service), the billing address information withdrawn very frequently - it comprises a location address for the telephone customer and, thus, is used advantageously to direct the provision of emergency services in cases where the calling party is unable to provide this location information or does not have sufficient time to supply the information. When a mobile subscriber initiates the emergency telephone call of a cell phone and reports an emergency situation, however, the factual address information A portion capable of being removed by the PSAP system of the cell phone caller is of no value in determining the present location of that mobile subscriber. Current technology - cell phone, by itself, does not include the ability to point, with any reasonable or useful degree of accuracy, the location of the mobile subscriber. Consequently, a number of systems has been proposed to assist in the determination of location. A system uses a triangulation process to determine an approximate location of the caller through an analysis of signal resistance measurements and / or propagation delay times of cellular communications. Another system uses the existing Global Positioning System 'GPS) with a CPS receiver fixed to the cell phone to obtain geo-coordinates for the mobile subscriber, with the obtained coordinates being transmitted to the PSAP system to be used for the services of the mobile subscriber. emergency. Knowing the location of the mobile subscriber does not compromise the sole importance of providing emergency services in response to an emergency 911 cellular call. It is also important that the emergency cellular call be routed to the appropriate PSAP system when the mobile subscriber moves away from his or her home area. For example, consider the situation where a mobile subscriber is busy on a cellular call. As the subscriber moves through the service area, an interruption of service is likely to occur. the call from a cell assigned to a mobile-switching center (the anchor MSC) to a cell assigned to another mobile-switching center (the server MSC). This interruption does not affect the continuation of the cellular call. However, it may affect the routing of an emergency service call. If the subscriber places a first cellular call on hold, and then initiates a second, cellular call for emergency services, the emergency call is being routed from-blindly via the server MSC to the anchor MSC which then sends the call to the PSAP system associated with the anchor MSC.

In the event that the PSAP system associated with the anchor MSC - differs from the PSAP system associated with the server MSC, the emergency 11 is routed incorrectly, possibly delaying the sending of emergency services personnel in this way to help the mobile subscriber. Consequently, there is a need for a system and method to ensure that emergency service calls from mobile subscribers are routed appropriately through the cell phone network to the correct PSAP system for processing and response.

COMPENDIUM OF THE INVENTION In a cell phone network that includes plural plurality. In each service area served by a different mobile service center, media are provided in each service center. mobile switching to signal to other mobile switching centers (in case of fading of area between mobile call service of a mobile subscriber (with information that allows the identification of the system of answer point of public accountability (PSAP) used to answer the 911 emergency telephone calls in the service area where the mobile subscriber is currently located.This information could include one or more of the following: routable number, reference to a routable number, or server MSC identification ( anchor) with which the correct PSAP that uses a search box is deduced.When multiple deviations of service area have occurred, the identification of PSAP is sent by the mobile switching center serving the mobile switching center of anchor at the time of call initiation, when necessary, the PSAP identification is relayed through of tandem mobile switching centers integrating means before reaching the mobile anchor switching center Consequently, the emergency call is routed from the anchor mobile switching center to the appropriate PSAP as specified by the PSAP identification instead of routing inappropriately to the PSAP system of the mobile anchor switching center.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the method can be obtained and apparatus of the present invention with reference to the following Detailed Description when taken in conjunction with the accompanying Drawings, wherein: Figure 1 is a block diagram of a cellular telephone system connected to a plurality of systems public safety answering point; and Figures 2 and 3 are network message sending diagrams illustrating the flow of messages in the system of Figure 1 with respect to the reporting of public security answering point information in cases of mobile station movement. area between services.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to Figure 1 wherein a block diagram of a cellular telephone system 10 that provides cellular telephone service through a geographical area is shown. The cellular telephone system 10 comprises a plurality of mobile switching centers (MSC) 12, each controlling the provision of cellular telephone service to a particular service area 14 within the geographical area. Each service area 14 comprises a plurality of cells 16 -. { only a few shown for simplification of the illustration, wherein each cell includes at least one base station 18 (BS) for performing radiofrequency communications with mobile stations (MS) located in close proximity. The base stations 18 are connected for communications with the mobile switching center 12 for the service area 14 within which the cells 16 are placed for those base stations. The mobile switching centers 12 are connected for communications to the public switched telephone network (PSTN) 22. The general operation of the cellular telephone network 10 as shown in Figure 1 to provide telephone communication with mobile stations 20 is well known to those skilled in the art, and will not be described in detail here. The telephone network may comprise an analogue advanced mobile telephone system (A PS), a Mobile Special Group (GSM) system, a digital D-AMPS system, a time division multiple access (TDMA) system, a system - multiple access code division (CDMA), or the like.

Connected to the public switched telephone network 22 is a plurality of public safety answering point (PSAP) systems 24. Each public security answering system 24 is used by emergency service providers (such as the police department, fire department, or rescue department) as a central point for receiving telephone calls from emergency services (eg, dial 911 calls) and the dispatch of emergency services personnel within an associated emergency service area 26. It will be noted that some of the mobile switching centers 12 (and in general their areas 14 - of service) are located within the emergency service area 26 managed by a public security answering system 24, while other mobile switching centers (and service areas) are located within the service-area of emergency managed by another public security check point system. It is also possible that the service area 14 of a mobile switching center 12 may receive service from more than one public security answering system 24 (as generally shown in the service area 14 (4)). The broken lines 38 indicate the dividing points between the emergency service areas illustrated 26 (1), 26 (2) and 25 (3). It is important that any cellular emergency call initiated from a mobile station 20 be handled by the public security answering system 24 for the emergency service area 26 within which the mobile station is located. Otherwise, the sending and / or arrival of emergency assistance could be misdirected or delayed. Under normal cell phone system operating conditions, this is not important as the cellular emergency call is handled by the mobile switching center 12 for the service area -14 where the emergency call originates (the MSC server ) and routed to the public security answering point system 24 associated with that particular server mobile switching center. Similarly, in the event that a service area 14 and its mobile switching center 14 are associated with a plurality of public safety answering point systems 24 (as in the service area 14 (3)), -the routing is made to the system 24 of public safety answering point associated with cell 16 currently serving the mobile station. When the mobile subscriber is busy on a first call, and is moving between the service areas 14, however, a communication link for that call is maintained through the mobile switching center 12 for the service area where the first call (the anchor SC) was originated, and in this way any cellular emergency call initiated at the same time as the first call (placing the first call on hold) is undesirably routed through the mobile switching center of anchor and the public switched telephone network 22 to the 24 point system of public safety-response associated with the anchor mobile switching center. Then, the sending and / or arrival of-emergency aid can be misdirected or delayed. The above problem associated with the routing of a cellular emergency call initiated at the same time that a first call en route from a mobile station moving in the service area can be better understood with reference to a specific related example. with the mobile station 20 'illustrated as being positioned in the serving area 14 (1) of Figure 1. The mobile station 10' is coupled (either through an origin or reception) on a first cell phone call in a manner well known to those experienced in the field while placed in the 14 (1) area of -service. This first call is routed through the mobile switching center 12 (1) (the anchor MSC) and, possibly, the public switched telephone network 22. Now suppose that the mobile station 20 'begins to move, along the path generally indicated by the arrow 28, between the service areas 12, and in fact moves from the service area 14 (1) through the service area 14 (2) for service area 14 (3) -without terminating the first call. As the mobile station moves, the system 10 passes the responsibility for that llarna first to the mobile switching center 12 (2) as the service-MSC, and then to the mobile switching center 12 (3) as the - Service MSC (with the mobile switching center 12 (2) convirring then in the MSC in tandem). All the time, however, the anchor mobile switching center 12 (1) remains - at the call with the first call communications being in ^ walked between the anchor MSC and the mobile service switching center 12 (3) through the center 12 (2) of mobile switching in tandem. If the mobile station 10 'were at this point in its travels along the arrow 28 to find an emergency situation 30 (which occurs within the cellular service area 14 (3) and the service area 26 (2) emergency) and - you want to originate a cellular emergency call at the same time with the continuous handling of the first call, the first flame, da can be placed in retention using well known means and the cellular emergency call initiated. Because the first call link with the mobile anchor switching center 12 (1) remains in place to continue with the handling of the first call (now on hold), the initiated cellular emergency call is also directed to the anchor mobile switching center through the mobile service switching center 12 (3) and the mobile switching center 12 (2) in tandem.

It will be noted, however, that the service area 26 (1) within which the service area 14 (1) · for the mobile switching center 12 (1) of anchor is placed is different than -the emergency service area 26 (2) into which is placed each service area 14 (3) for the mobile service switching center 12 (3). Consequently, the initiated cellular emergency call is routed from the mobile anchor switching center 12 (1) to its public security answering system 24 (1) for the service area 26 (1) of emergency instead of system 24 (2) of public security answering point for area 26 (2) of emergency service where emergency situation 30 is occurring. Reference is now made to Figures 2 and 3 where network message sending diagrams are shown illustrating the signal flow in system 10 of Figure 1 which responds to to the cases of movement of mobile station of area between services. When a moving mobile station 20 initiates a cellular emergency call, the switching center 12 - currently in service - generates a message 32 including a number of parameters 34 for transmission back to any - mobile switching centers previously in service. The message 32 is referred to in the Sender as a Return Information Call (INFOBAC) which is generated to include parameters 3 (1) - 3 C) comprising the mobile identification number (MIN) of the mobile station 20, the number electronic serial number - (ESN) of the mobile station, the trunk between the mobile switching centers to carry the call (IMSCCID - identification of switching center circuit between mobile), and the number of - billing identification for the call (BILLID), respectj_ vamente. Of course, it will be understood that message 32 may include additional or different parameters, if necessary, - in accordance with the appropriate owner or public communications protocol. The message 32 however further includes a parameter 34'5) comprising an identification of the public security answering system (PSAPID) 24 assigned to the emergency service area 26 within which the mobile switching center is located. that sends the signal. This identification may comprise a routable number, a reference to a routable number, or an identification of the service SC from which the PSAP identification may be found. through the use of a search box. Sensitive to the receipt of the message 32, the mobile receiving switching center 12 generates a knowledge message 36 referred to herein as an Information Backward (infoback) message. Referring now again to Figure 1, together - with Figure 2, and with particular reference to the example above - discussed with respect to the mobile station 20 'in motion, when the mobile station moves from the area 14 (1) of service to the service area 14 (2), the mobile switching center 12 (1) that handles a first cellular call when it is started -converts to the anchor MSC and the switching center 12 (2) --mobile for the service area 14 (2) it becomes the server MSC. When an emergency 30 is found in area 14 (2) -service, and a cellular emergency call is initiated 'as a subsequent call with any previous calls -probably being placed on hold), the message 32 is -generated by the mobile service switching center 12 (2) and transmitted to the anchor mobile switching center 12 (1). This message includes parameter 34 '5) which identifies the public safety answering point system 24 assigned to the emergency service area 26 within which the service area 14 (2) for the switching center 12 (2) mobile service is placed. The message 32 further includes the parameter -34 (3) IMSCCID identifying the circuit connection between the mobile service switching center 12 (2) and the center 12 (1) of anchor mobile switching. In response to the receipt of the message 32, the knowledge item 36 is sent back to the mobile service switching center 12 (2). The anchor mobile switching center 12 (1) then consequently handles the emergency call by routing the call to the public security answering system 24 for the center 12 (2) of - mobile service switching instead of the system 24 of public safety answering point for center 12 (1) of mobile anchor mutation, in this case, public safety answering point systems 24 for service areas 14 (1) and 14 (2) not they are different, and in this way the message 32 does not change the shape of the call that otherwise would have been handled absent the use of the message. Now also referring to Figure 3, again with particular reference to the example discussed above with respect to mobile station 20 'in motion, suppose that the mobile station next moves from the service area 14 (2) to the area 14 (3) service. When emergency 30 is in service area 14 (3), and a cellular emergency call is initiated (as a subsequent call with any previous call (s) probably being placed on hold), message 32 will be generated by the mobile service switching center 12'3) and transmitted to the anchor mobile switching center 12 (1) via the mobile switching center-2 in tandem. This message 32 includes parameter 34 (5) which identiH c) the public security answering point system 24 assigned to the emergency service area 26 within which the service area 14 (3) is placed for the mobile service switching center 12 (3). Parameter 3413 (IMSCCID included in this case identifies the circuit connection between the mobile service switching center 12 (3) and the mobile switching center 12 (2) in tandem, the mobile switching center 12 (1) of The anchor then consequently handles the emergency call by routing the call to the public safety answering point system 24 for the switching center 12 (3) - service mobile instead of the security answering point system 24 Public for the anchor mobile switching center 12 (1) In this case, the public safety answering point systems 24 for the service areas 14 (1) and 14 (3) are different., and in this way message 32 changes the way that the claim would otherwise have handled the -use of the message. In the situation where a service area 14 and its associated mobile switching center are serviced by the public safety answering point systems 24 (as in the service area 14 (4)), the mobile switching center In general, they recognize from cell 16 serving the mobile station the location of the mobile station and determine which of the plurality of public security answering system systems is the correct system to handle an emergency call. started. The message 32 generated and transmitted by the mobile switching center 12 then identifies the correct public security answering system 24 to handle the emergency call. Even though a preferred embodiment of the method and apparatus of the present invention has been illustrated in the accompanying Drawings and described in the above Detailed Description, it will be understood that the invention is not imitated to the described embodiment, but is capable of numerous redispositions, --modifications and substitutions without abandoning the spirit of the invention as set forth and defined by the following claims. In particular, it will be understood that the present invention may be employed in connection with any cellular telephone system, using any public or private communications protocols.

Claims (10)

CLAIMS:

1. - A cell phone system that includes a plurality of mobile switching centers, the mobile switching centers generating, to consider cases of mobile station fading between mobile switching centers, a message identifying a service processing center for the mobile station. emergency associated with one currently serving the mobile switching centers, the generated message being transmitted from the mobile service switching center to a service anchor one previously of the switching centers for use by the center. mobile anchor switching or clamping in the direction of an emergency service call made from the mobile station.

2. The system of claim 1, wherein the emergency service processing center comprises a public security answering point system (PSAP).

3. - The system of claim 1, wherein the message includes a useful parameter for identifying the emergency services of the processing center associated with the mobile service switching center.

4. - A method for cell phone network operation, comprising the steps of: generating a message in a mobile switching center - which currently serves a moving mobile station - to take into account the fading of the mobile station from a mobile switching center previously serving the mobile station in motion to the mobile switching center which, since the service is currently occurring, the message generated by identifying a service processing center. emergencies associated with the mobile switching center that currently serves; and transmitting the message from the mobile switching center currently in service to the previous mobile switching center in service for use by the mobile switching center previously in service in directing an emergency service call initiated by the mobile station in motion.

5. The method as in claim 4, wherein the emergency service processing center comprises a public security answering system (PSAP).

6. - The method as in rei indication 4, where -includes a useful parameter to identify the emergency service processing center associated with the mobile switching center in service. 7.- A cell phone system, comprising. an anchor mobile switching center that handles the initiation of a cellular call for a mobile station in motion, and a mobile switching center in service that currently handles the cellular call for the moving mobile station; and which includes elements for generating a message transmitted to the anchor mobile switching center, the message identifying an emergency service processing center associated with the mobile service switching center and used by the mobile switching center of anchor when directing a call - emergency services made from the moving mobile station. to the identified emergency services processing center. 8. - The system of claim 7, including - 0 in addition to at least one mobile tandem switching center connected between the mobile switching center in service and the anchor mobile switching center, the message generated by - the center of mobile switching in service routed through - from the at least one mobile switching center in tandem to the anchor mobile switching hub 5. 9. - The system of claim 7, wherein the emergency service processing center comprises a public security answering system (PSAP). 10. - The system of claim 7, wherein the -0 message includes a useful parameter for identifying the emergency services center associated with the mobile service switching center. 5