Abstract:
An emergency information system comprises an interface and a processing system. The interface is configured to receive first call signaling for an emergency call from a call processing system wherein the first call signaling indicates a call back number. The processing system is configured to process the first call signaling to determine a destination for the emergency call, generate second call signaling indicating a key and the destination, and generate a database message indicating the key and the call back number. The interface is further configured to transfer the second call signaling to the call processing system and transfer the database message to a database system.

Description:
RELATED APPLICATIONS 
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     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     MICROFICHE APPENDIX 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The field of the invention relates to telecommunication technologies, and in particular, to the provisioning and delivery of emergency call services in telecommunication networks. 
     2. Description of the Prior Art 
     Emergency call services, such as 911, are a vital component of most telecommunication services. The provisioning and delivery of emergency services requires a complex interaction between services providers, such as telecommunication carriers, and public safety elements. One important aspect of providing emergency call services is the ability for an emergency responder to call back a caller in the event of a disconnection. However, recent advances in telecommunication technologies have reduced the ability for emergency responders to call back callers. 
     In the prior art, most users placed emergency calls over the public switched telephone network (PSTN). In the PSTN, a caller can be identified by the physical line over which the emergency call is placed. Even in a case where the line involved includes a caller identification block, the line remains identifiable by the originating switch. The phone number associated with the line can be passed on to the emergency service responder at the appropriate public safety answering point (PSAP). In the event of a service disconnect, the emergency responder can out dial the phone number to reconnect with the caller. 
     One new telecommunication technology is Voice over Internet Protocol (VoIP). In the case of VoIP, end users have a wide variety of service options, including the ability to block network elements from passing on their call back number to other network elements. In addition, end users are able to provide call back numbers that, when dialed, do not reach back to the user. Unfortunately, the call back number of a VoIP caller cannot be identified by a phone line, as opposed to in the PSTN. As a result, emergency responders are often times unable to call back VoIP-callers in the event of call disconnects. 
       FIG. 1  illustrates a communication network  100  in an example of the prior art for providing call back numbers to emergency responders for VoIP callers. Communication network  100  includes VoIP network  110 , session initiation protocol (SIP) proxy  105 , SIP phone  101 , emergency information system (EIS)  115 , automatic location identification (ALI) database  116 , PSTN  120 , and PSAP  125 . 
     In this example, a user using SIP phone  101  places an emergency phone call, such as by dialing 911. Typically, SIP proxy  105  communicates with EIS  115  to determine an appropriate PSAP for the call. EIS  115  selects the PSAP and provides the PSAP information to SIP proxy  105 . EIS  115  also determines service information for the call, such as the location of and call back number for SIP phone  101 . EIS  115  provides the service information to ALI database  116 , along with a key. ALI database stores the service information in association with the key. EIS  115  also provides the key to SIP proxy  105 . 
     SIP proxy  105  then communicates with elements of VoIP network  110 , such as a media gateway controller, to setup a call leg from SIP phone  101  to PSTN  120 . The media gateway controller communicates with elements of PSTN  120 , such as a selective router, to establish a call leg through PSTN  120  to PSAP  125 . Included in the call setup process, the key is communicated from SIP proxy  105  to PSAP  125  in the form of an ESRK, ESRN, or ESQK. PSAP  125  queries ALI database  116  with the key to obtain the service information stored by ALI database  116  in association with the key. In this manner, operators at PSAP  120  are able to call back the user in the event of a service disconnection. 
       FIG. 2  illustrates a flow diagram in an example of the prior art to more clearly describe how a call back number is provided to a PSAP. To begin, SIP phone  101  transmits call signaling, such as a SIP invite message, to SIP proxy  105 . The SIP invite message includes several information fields. One of the fields is a from field that indicates the sender of the message. The from field is typically populated with a user identification, such as a SIP user ID. SIP user IDs are often times in the form of userID@network.com. Another field is the called number field. In this case, the called number field indicates 911. 
     In response to the first invite message, SIP proxy  105  transmits another SIP invite to EIS  115 . The second SIP invite also includes the user ID in the from field. EIS  115  performs a database lookup to a database system to determine a call back number based on the user ID. The database system typically contains user IDs stored in association with 10 digit telephone numbers. 
     Upon determining the call back number, EIS  115  transfers the key and call back number to ALI database  120 . ALI database  120  stores the call back number in association with the key. EIS  115  also transfers call signaling to SIP proxy  105  indicating the appropriate PSAP and the key. SIP proxy  105  proceeds to setup the emergency call between SIP phone  101  and PSAP  120 . During the call setup process, the key is passed to PSAP  120 . PSAP  120  queries ALI database  120  with the key to determine the call back number for the call. 
     Eventually, call communications commence between an operator at PSAP  120  and the user at SIP phone  101 . In the event of an on-hook event or some other service disruption, the operator can call back the user using the provided call back number. Call communications can be re-established and emergency service can continue. 
     As illustrated in  FIG. 2 , the prior art contains significant drawbacks in the provisioning and delivery of emergency call services. For example, EIS  115  is required to perform a database look-up based on a user ID in order to determine a call back number for the emergency call, costing valuable time and resources. In addition, storing and maintaining call back numbers at EIS  115  is costly and error prone. Further problematically, users are able to hack into the various fields of SIP invite messages. This reduces the reliability of user IDs provided from SIP phones and further impacts the ability of emergency responders to call back VoIP callers in the event of service disruptions. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention helps solve the above problems and other problems by providing systems, methods, and software for providing a call back number from a call processing system directly to an emergency information system, rather than requiring the emergency information system to perform a resource intensive database look-up based on a user identification. In addition, the call back number is provided to the emergency information system in a secure manner, rather than relying upon user-accessible data fields. 
     In an embodiment of the invention, an emergency information system comprises an interface and a processing system. The interface is configured to receive first call signaling for an emergency call from a call processing system wherein the first call signaling indicates a call back number. The processing system is configured to process the first call signaling to determine a destination for the emergency call, generate second call signaling indicating a key and the destination, and generate a database message indicating the key and the call back number. The interface is further configured to transfer the second call signaling to the call processing system and transfer the database message to a database system. 
     In an embodiment of the invention, the emergency information system is configured to determine the call back number from the first call signaling. 
     In an embodiment of the invention, the first call signaling comprises a session initiation protocol (SIP) invite message. 
     In an embodiment of the invention, the call processing system is configured to insert the call back number into a privacy asserted identity field of the SIP invite message. 
     In an embodiment of the invention, the processing system is configured to process the privacy asserted identity field to determine the call back number. 
     In an embodiment of the invention, the call processing system transfers the key to the destination and wherein the destination transfers a query indicating the key to the database system and wherein the database system returns a response indicating the call back number in response to the query. 
     In an embodiment of the invention, the database system comprises an automatic location identification (ALI) database system. 
     In an embodiment of the invention, the destination comprises a public safety answering point (PSAP). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  illustrates a communication network in an example of the prior art. 
         FIG. 2  illustrates the operation of a communication network in an example of the prior art. 
         FIG. 3  illustrates a communication system in an embodiment of the invention. 
         FIG. 4  illustrates the operation of a communication system in an embodiment of the invention. 
         FIG. 5  illustrates a communication system in an embodiment of the invention. 
         FIG. 6  illustrates the operation of a communication system in an embodiment of the invention. 
         FIG. 7  illustrates a computer system in an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 3-7  and the following description depict specific embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple embodiments of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
     First Embodiment Configuration and Operation 
     FIGS.  3  and  4   
       FIG. 3  illustrates communication system  300  in an embodiment of the invention. In this embodiment, a call back number is passed from a call processing system directly to an emergency information system (EIS), rather than requiring the EIS to perform a resource intensive database look-up based on a user identification. In addition, the call back number is provided to the EIS in a secure manner, rather than relying upon user-accessible data fields. 
     Communication system  300  includes communication network  310 , communication system  301 , call processing system (CPS)  305 , PSAP  325 , EIS  15 , and ALI database  316 . Communication network  310  could be any network or collection of networks capable of operatively transporting communications between CPS  305 , EIS  315 , communication system  301 , and PSAP  325 . Communications could comprise signaling as well as bearer traffic. 
     CPS  305  could be any system capable of communicating with EIS  315 , communication system  301 , and communication network  310 . Communication system  301  could be any system capable of communicating with CPS  305  and communication network  310 . Communication system  301  could be a communication device, as well as a collection of multiple communication devices, such as a phone device and an access device. PSAP  325  could comprise any PSAP capable of communicating with ALI database  316  and communication network  316 . EIS  315  could be any system capable of communicating with CPS  305 , ALI database  316 , and communication network  310 . 
       FIG. 4  is a flow diagram illustrating the operation of communication network  300  in an embodiment of the invention. In this embodiment, the provisioning and delivery of a call back number is illustrated. 
     To begin, communication system  301  transmits call signaling to CPS  305  for an emergency call. The call signaling indicates that the call is an emergency call. The call signaling also includes a user identification. CPS  305  receives the call signaling from communication system  301  and processes the call signaling to determine a call back number for the call. CPS  305  transmits new call signaling to EIS  315  indicating the call back number. The new call signaling could also include the user identification, as well as other information. 
     EIS  315  processes the call signaling to determine a key for the call and to select a PSAP for the call. In this case, the selected PSAP is PSAP  320 . EIS  315  transfers a database message to ALI database  320  indicating the key and the call back number. EIS  315  also generates new call signaling indicating the PSAP and the key, and transfers the new call signaling to CPS  305 . 
     CPS  305  processes the new call signaling to setup the call over communication network  310  between communication system  301  and PSAP  320 . In the course of call setup, the key is transferred from CPS  305  to PSAP  320 . PSAP  320  transfers a query to ALI database  320  indicating the key. ALI database  320  processes the query to determine the call back number stored in association with the key. ALI database  320  returns a response to PSAP  320  indicating the call back number. Eventually, the emergency call commences between PSAP  320  and communication system  301 . At anytime, a service disruption could occur. In the event of a service disruption, PSAP  320  can place a call to communication system  301  utilizing the call back number and the call can be re-established. 
     As illustrated, communication system  300  provides for securely and reliably providing a PSAP with a call back number for an emergency call. In particular, CPS  305  determines the call back number and provides the call back number to EIS  315 , rather than requiring EIS to perform a database look-up to determine the call back number. In addition, CPS  305  determines the call back number without relying upon user-accessible data fields. In this manner, processing resources of EIS  315  are conserved and call back numbers are protected from user interference. 
     Second Embodiment Configuration and Operation 
     FIGS.  5  and  6   
       FIG. 5  illustrates communication network  500  in an embodiment of the invention. Communication network  500  includes packet network  510 , SIP proxy  505 , SIP phone  501 , PSTN  520 , EIS  515 , PSAP  525 , and ALI database  516 . SIP proxy  505  is operatively coupled to packet network  510 . SIP phone  501  is also operatively coupled to packet network  510 . EIS  515  is operatively coupled to packet network  510  and ALI database  516 . PSTN  520  is operatively coupled to packet network  510  and PSAP  525 . Both packet network  510  and PSTN  520  could include elements that are not shown for purposes of clarity. Packet network  510  could be a single packet network or a collection of packet networks. 
     It should be understood that EIS  515  is depicted as directly connected to ALI database system  516  for illustrative purposes only, and that EIS  515  could be in communication with ALI database system  516  over any type of communication network. Similarly, it should be understood that PSAP  525  is depicted as directly connected to ALI database system  516  for illustrative purposes only, and that PSAP  525  could be in communication with ALI database system  516  over any type of communication network. 
       FIG. 6  illustrates the operation of communication network  500  in an embodiment of the invention. To begin, it is assumed that a user has registered SIP phone  501  with SIP proxy  505 . During the registration process, the user and device are authenticated. SIP proxy  505  typically stores vital information, such as a call back number for the user, at the time of registration. The information could be obtained from the user during the registration process or could be permanently stored at another location and accessed by SIP proxy  505  during the registration process. 
     Turning to  FIG. 6 , SIP phone  501  transmits a SIP invite message SIP to proxy  505  for an emergency call. The invite message indicates that the call is an emergency call. The invite message also includes a user identification, such as in the form of userID@sipnetwork.com. SIP proxy  505  receives the invite message from SIP phone  501  and processes the message to determine a call back number for the call. For example, SIP proxy  505  could look-up the call back number based on the user ID included in the invite message or an IP address included in the invite message, as well as by using other information well known to those skilled in the art. 
     SIP proxy  505  then transmits a new SIP invite message to EIS  515  indicating the call back number. In particular, SIP proxy  505  creates a privacy asserted identity field in the new invite message and populates the privacy asserted identity field with the call back number. The privacy asserted identity field is used among trusted SIP entities (typically intermediaries) to carry the identity of the user sending a SIP message as it was verified by authentication. The call back number could be provided in the form of a telephone uniform resource indicator (TEL-URI) as is commonly understood in the art. For instance, the privacy asserted identity field could read 555-555-5555@sipnetwork.com. The invite message could include additional information. 
     EIS  515  processes the invite message from SIP proxy  505  to determine a key for the call and to select a PSAP for the call. In this case, the selected PSAP is PSAP  525 . The key could be in the form of an ESRK, ESRN, or ESQK as is well understood in the art. Other types of keys are possible. EIS  515  also pulls the 10 digit phone number from the privacy asserted identity field and generates a database message indicating the 10 digit phone number. EIS  515  then transfers the database message to ALI database  520  indicating the key and the 10 digit call back number. EIS  515  also generates another new SIP invite message indicating the PSAP and the key and transfers the new call signaling to SIP proxy  505 . 
     SIP proxy  505  processes the new invite message to setup the call over packet network  510  and PSTN  520  between SIP phone  501  and PSAP  525 . In the course of call setup, the key is transferred from SIP proxy  505  to PSAP  525 . PSAP  525  transfers a query to ALI database  520  indicating the key. ALI database  520  processes the query to determine the call back number stored in association with the key. ALI database  520  returns a response to PSAP  525  indicating the call back number. 
     At anytime during the call between PSAP  525  and SIP phone  501 , a service disruption could occur. In such a case, PSAP  525  can place a call to communication system  501  utilizing the call back number and the call can be re-established. 
     The above illustration depicts a scenario whereby PSAP  525  is operatively coupled to PSTN  520 . Due to this constraint, EIS  515  typically passes a 10 digit telephone number to ALI database  516 . The 10 digit telephone number is derived by EIS  515  from the TEL-URI described in the privacy asserted identity field of the SIP invite message received from SIP proxy  505 . It should be understood that PSAP  525  could be a SIP enabled PSAP that is capable of communicating directly over a packet network, rather than traversing the PSTN. In such a case, SIP proxy  505  could fill with privacy asserted identity field with a SIP URI, rather than the TEL URI. Alternatively, SIP proxy  505  could data fill the field with both the TEL URI and the SIP URI. Regardless, EIS  515  could provide the SIP URI to ALI database  516 . In turn, PSAP  525  could query ALI database  516  for the SIP URI. PSAP  525  could then connect with SIP phone  501  using the SIP URI, as is well understood in the art. 
     As illustrated, communication system  500  provides for securely and reliably providing a PSAP with a call back number for an emergency call. In particular, SIP proxy  505  determines the call back number and provides the call back number to EIS  515 , rather than requiring EIS  515  to perform a database look-up to determine the call back number. In addition, SIP proxy  505  determines the call back number without relying upon user-accessible data fields. In this manner, processing resources of EIS  515  are conserved and the integrity of call back numbers are protected. 
     Computer System 
       FIG. 7  illustrates computer system  700  in an embodiment of the invention. Computer system  700  includes interface  720 , processing system  730 , storage system  740 , and software  750 . Storage system  740  stores software  750 . Processing system  730  is linked to interface  720 . Computer system  700  could be comprised of a programmed general-purpose computer, although those skilled in the art will appreciate that programmable or special purpose circuitry and equipment may be used. Computer system  700  may use a client server architecture where operations are distributed among a server system and client devices that together comprise elements  720 - 750 . 
     Interface  720  could comprise a network interface card, modem, port, or some other communication device. Signaling interface  720  may be distributed among multiple communication devices. Processing system  730  could comprise a computer microprocessor, logic circuit, or some other processing device. Processing system  730  may be distributed among multiple processing devices. Storage system  740  could comprise a disk, tape, integrated circuit, server, or some other memory device. Storage system  740  may be distributed among multiple memory devices. 
     Processing system  730  retrieves and executes software  750  from storage system  740 . Software  750  may comprise an operating system, utilities, drivers, networking software, and other software typically loaded onto a general-purpose computer. Software  750  could also comprise an application program, firmware, or some other form of machine-readable processing instructions. When executed by the processing system  730 , software  750  directs processing system  730  to operate as described for remote service testing systems  200 ,  400 , and  500 . Also when executed by the processing system  730 , software  750  directs processing system  730  to operate as described for emergency information system  315  and emergency information system  515 .