# Patent

## Title
Emergency call completion for VoIP based on location of call originator

## Abstract

Emergency calls placed from telephone devices connected to a data network are completed to the appropriate public safety answering point (PSAP). In one embodiment of the present invention, a method for completing an emergency call comprises receiving a call from a device on a data network, the call destined for an emergency service, the device having a physical location, obtaining a telephone number of an emergency call center that handles emergency calls for the physical location of the device, and routing the call to the emergency call center using the telephone number.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part application of application Ser. No. 10/774,689, filed Feb. 10, 2004.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a completing emergency calls placed from telephone devices connected to a data network.
2. Description of the Related Art
Traditional phone systems include local carriers and long distance carriers. Local carriers connect calls within a given local area, while long distance carriers carry calls between the local carriers. The telephone lines from a home or office connect directly to a wire center, which is often referred to as a central office. The central office has one or more switches, which route or direct telephone calls from one destination to another.
Telephone numbers typically include an area code, and a seven digit telephone number. The seven digit telephone number includes a three digit central office number, and four digit central office extension. The three digit central office number directs calls to a particular central office. Once the call reaches the desired central office, the four digit extension directs the call to a line that is served by that central office. Area codes are typically used for long distance phone calls, as discussed below.
Local telephone calls within a small area are often completed within a single central office. In this configuration, calls within the same area are served by the same central office. The central office connects the incoming call to the destination number. If the area is larger however, communication with a second central office may be necessary. The two central offices are typically connected by a trunk, which is a line between the central offices. The destination receives the call from the first central office and then directs it to the appropriate destination, based on the dialed phone number.
Each area code, as mentioned above, corresponds to a particular group of central offices. When a user dials an area code and then the seven digit telephone number, the central office analyzes the dialed number. If the dialed number is located within the Local Transport and Access Area (LATA), then the call is directed to the appropriate central office. A LATA, or local calling area, is typically a contiguous geographic area. If the dialed number is outside of the LATA, the local central office checks its database to determine which long distance company the user has selected for making the call. The local central office then switches the call to lines that are connected to the long distance company's nearest switch, often referred to as a point of presence (POP). Once the long distance company receives the call, it analyzes the phone number and routes the call across the long distance network to the POP that is closest to the called number. That POP routes the call back to a local central office that is near the destination phone, which then completes the call as described above.
The local and long distance companies incur costs for the equipment, switching calls, and maintaining their equipment. All of these costs are eventually passed on to the consumer. Because local calls involve one or two switching stations owned by one company, the costs of a local telephone call are typically low. Typically, a consumer pays a fixed fee for a unlimited amount of local calls. However, because long distance calls are transferred from the local telephone company, to a long distance carrier, and then back to a local telephone company, the cost of a long distance call is greater than a local call. Typically, long distance calls are charged by the minute. However, rates vary depending on a number of factors, such as the number of switches between the originating and destination numbers and taxes. For example, long distance calls between countries may be higher than long distance calls within a given country.
A continuing need exists for a method and apparatus that is capable of reducing the costs associated with long distance telephone calls. One solution that meets this need is the use of virtual numbers to complete calls over a data network, as described in U.S. patent application Ser. No. 10/774,689, filed Feb. 10, 2004 and entitled “Method and Apparatus for Placing a Long Distance Call Based on a Virtual Phone Number”, which is hereby incorporated by reference in its entirety. However, a problem that arises with this solution is the placement and completion of emergency calls. Typically, such calls are placed by dialing “911” and are completed to a public safety answering point (PSAP) based on the physical location from which the call was placed. In the conventional public switched telephone network (PSTN), the determination of the physical location from which a call is placed is quite simple, as the telephone devices at each location are hard-wired to switching equipment in a central office. However, with calls placed over a data network, the telephone devices are typically not directly connected to the call switching and routing equipment in the network. Thus, a need arises for a technique by which emergency calls placed from telephone devices connected to a data network may be completed to the appropriate PSAP.
SUMMARY OF THE INVENTION
The present invention provides the capability for emergency calls placed from telephone devices connected to a data network to be completed to the appropriate public safety answering point (PSAP). In one embodiment of the present invention, a method for completing an emergency call comprises receiving a call from a device on a data network, the call destined for an emergency service, the device having a physical location, obtaining a telephone number of an emergency call center that handles emergency calls for the physical location of the device, and routing the call to the emergency call center using the telephone number.
In one aspect of this embodiment, the call may be placed by dialing 911. The telephone number of the emergency call center may be obtained based on a telephone number of the device. The telephone number of the emergency call center may be a physical telephone number on a switched telephone network. The data network may comprise the Internet.
In one embodiment of the present invention, an apparatus connected to a data network is operable to receive a call from a device on the data network, the call destined for an emergency service, the device having a physical location, the apparatus further operable to obtain a telephone number of an emergency call center that handles emergency calls for the physical location of the device and to route the call to the emergency call center using the telephone number.
In one aspect of this embodiment, the call may be placed by dialing 911. The telephone number of the emergency call center may be obtained based on a telephone number of the device. The telephone number of the emergency call center may be a physical telephone number on a switched telephone network. The data network may comprise the Internet.



BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the drawings described below:
FIG. 1 is a block diagram showing an overview of an exemplary system according to an embodiment of the present invention;
FIG. 2 is a diagram showing an exemplary embodiment of the present invention; and
FIG. 3 is a diagram showing another exemplary embodiment of the present invention.
FIG. 4 is a diagram showing another exemplary embodiment of the present invention.
FIG. 5 is a diagram showing another exemplary embodiment of the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Increasingly, phone companies are using computer or data networks such as the Internet, to transport long distance calls from one destination to another. Transferring voice calls over a data network is typically accomplished by converting analog voice signals into data packets. This is typically, but not necessarily, accomplished using the well-known Voice over Internet Protocol (VoIP). Transporting calls over computer networks allows local phone companies to bypass long distance carriers. Additionally, because computer network infrastructures are already in place, the cost of transporting calls over computer networks is greatly minimized.
The present invention provides a method and apparatus for minimizing the cost of a long distance call by transporting voice traffic over computer networks. In one embodiment, the present invention comprises a method and apparatus for transmitting voice information between originating and destination points. The originating and destination points may include, but are not limited to, telephones, fax machines, pagers, computers, two way radios, cellular telephones, or telephones operatively connected to the public switched telephone network (PSTN). In a preferred embodiment, the originating and destination points are telephones operatively connected to the PSTN.
The two telephones can be, but do not have to be, operatively connected to separate networks, and each network is operatively connected to its own intermediate point. The intermediate points, which are preferably operatively connected by a computer network, allow the two telephone users to communicate based on the virtual number that is entered by the user of the originating telephone.
The area code of the virtual number is preferably within the local calling area of the originating telephone. In an exemplary embodiment, each virtual number is assigned to a destination telephone. The assignment information is stored in a memory, and can be referenced to determine which destination telephone number a virtual number is assigned to. The memory may, but does not have to be, operatively connected to the two intermediate points. Operatively connecting a memory to each of the two intermediate points allows the delay between receiving a number and determining its destination to be minimized.
In an exemplary embodiment, when a virtual number is received by a first intermediate point, the call may be routed from the first intermediate point to a second intermediate point that is within the local calling area of the destination telephone. The second intermediate point then directs the call to the destination telephone. The two intermediate points can direct a call to any destination number, regardless of the distance between the two telephones. This allows a user to access a long distance telephone using only a local virtual phone number, and provides the advantage of reducing the cost of the call.
Information may be transmitted on the originating and destination networks in any manner known to those skilled in the art. This may include, but is not limited to, information in analog or digital format. Additionally, any type of information may be transmitted between the two points on the originating and destination networks. This may include, but is not limited to, voice, data, or facsimile transmissions.
In one embodiment, the present invention comprises a set of routers distributed at different geographical areas. Each router is operatively connected to a computer network such that they are capable of communicating with each other. Each of the routers are preferably operatively connected to one or more originating or destination networks to receive and process telephone calls.
The router is preferably capable of providing an interface between a central office and the computer network. This may include, but is not limited to, converting data into a format capable of transmission over the computer network. In one embodiment, the router may comprise any computing device known to those skilled in the art. For example, in some embodiments the router may comprise a processor, such as a computer. Alternately, the router may comprise a router that is modified to interpret phone numbers and convert voice signals into data packets. In other embodiments, the router may comprise a server, or proxy server.
In one embodiment, the router receives and interpret a virtual phone number transmitted from an originating network. After processing a phone number to determine its destination, the router connects to another router that is connected to the destination network. Once a connection is established between the originating and destination routers, the originating router converts the voice data into data packets using a desired protocol, for example, VoIP or VoP. Preferably, the process of converting the voice signals into data packets is performed on a real-time, continuous basis. Each router can also be capable of converting the data packets back into voice data on a real-time, continuous basis. Such conversion, however, need not be performed by the router.
Data conversion on a real-time, continuous basis allows data to be transmitted between the originating and destination networks and the computer network with a substantially minimal amount of delay. This provides the advantage of allowing the originating and destination user to communicate with substantially minimal audible distortion. This also allows the two users to communicate over long distances while minimizing the cost of the call.
In one embodiment, a virtual phone number is assigned to a phone number on the destination network (“physical number”). The virtual phone number is assigned to a local router, such as a proxy server. This may be done by updating the memory that stores the virtual numbers and the physical number that they are assigned to. Each virtual phone number serves as a alias for, and directs calls to, a destination physical number. The virtual phone number does not exist on any physical device on the originating or destination network. Thus, calls do not have to be routed through any physical device on the originating or destination networks, which reduces the complexity and costs of routing a call.
FIG. 1 is a block diagram showing an overview of an exemplary system according to an embodiment of the present invention. As shown in FIG. 1, user 101 places a call to user 103. In order to do so, user 101 dials the virtual number that is assigned to the physical number of user 103. As shown in FIG. 1, user 101 dials the number, “202-424-1382.” This is a local call for user 101, and allows the user 101 to access router 105. In order to direct the phone call to the appropriate destination, router 105 communicates with a routing table 107. Preferably, routing table 107 is included in router 105. However, in some embodiments it may be a separate element, or part of another element can communicate with router 105.
The router 105 communicates with the routing table 107 to determine which call router 109 the virtual phone number “202-424-1382” corresponds to. In this exemplary embodiment, the routing table includes the physical number that is assigned to the virtual number and information that instructs router 105 to connect to a second router 109. The routing table determines which router 109 to connect to based on the proximity of router 109 to user 103. The router 109 that is chosen is preferably within the local calling area of user 103, and may be positioned closest to user 103.
Once this is determined, router 105 transfers the call to router 109 via a computer network 111. When the call is transferred from router 105 to router 109, the virtual numbers, or its equivalents, are included in the transmitted information. When the call reaches router 109, the router 109 communicates with the routing table 113 to determine what destination number the virtual number is assigned to. Based on this communication, router 109 determines that the destination phone number is “732-528-2603,” which corresponds with user 103. A connection is then established between router 109 and user 103. The connection may include, but is not limited to, a connection via, for example, the Internet protocol. Once the connection is established, user 101 and user 103 can communicate without incurring typical long distance charges.
FIG. 2 is a diagram showing an exemplary embodiment of the present invention. As shown in FIGS. 1 and 2, multiple virtual numbers 301 may be assigned to a physical number. In this embodiment, each router 105 in a different geographical area may have a different virtual number. Alternately, each router 105 may be accessed using a plurality of virtual numbers. Each virtual number preferably allows an originating user 101 to dial a number within their local area code in order to access a single destination user 103. This provides the advantage of allowing users in different geographical locations to communicate with user 103 while only dialing a local number. In this embodiment, the multiple users 101 may communicate with user 103 simultaneously or independently.
FIG. 3 is a diagram showing another exemplary embodiment of the present invention. In this embodiment, one or more virtual numbers may be assigned to multiple physical numbers 301. In other words, a virtual number may be used to call more than one physical number 301. The calls may be directed to their assigned physical number 301 in any desired manner, as described below.
In one embodiment the virtual number may be assigned such that the server 109 rings the physical devices 301 all at once, or one at a time. Information regarding the order of routing may be stored in the routing table 113. If all of the devices ring at the same time, then the call is routed to the physical number 301 that answers first. If each phone 301 rings one at a time, the user has the option of rolling over to the next physical number in a random order or sequentially by a predefined order.
A virtual number that is assigned to a physical device may be changed upon a users request. This can be done quickly and with minimal cost by reprogramming the routing table, such as routing table 107 shown in FIG. 1. Preferably, this change can be done with minimal manual intervention. However, in some embodiments a router may be reprogrammed manually.
FIG. 4 is a diagram showing another exemplary embodiment of the present invention, In this embodiment, a 911 emergency service may be activated. A user of the virtual number telephone service described above may subscribe to 911 emergency service using the components shown in FIG. 4. Using a data entry system 402, such as a personal computer, telephone, etc., a user communicates with a database system 404 over network 111. In particular, the user transmits physical address information 406 identifying the physical location for which 911 emergency service is to be activated. A telephone number corresponding to the physical location of the user's service is also transmitted or associated with the physical address information. The physical address information and user telephone number is transmitted via network 111 to database system 404, which is a database storing information including telephone numbers of public safety answering points (PSAPs) that correspond to physical addresses. A PSAP is a facility, such as a call center, where 911 emergency telephone calls are received and then routed to the proper emergency services. The physical address information is preferably translated to geocoding information 408 before transmission to database system 404. Database system 404 receives the geocoding information and the user telephone number and maps the user telephone number to a telephone number of the PSAP that serves the user location. In particular, database system 404 uses the geocoding information to determine the PSAP that serves the physical location and stores one or more database records that map the user telephone number to the telephone number of the PSAP serving the user location. Database system 404 then transmits a confirmation 410 indicating that the mapping of the user telephone number to the PSAP telephone number has been successfully completed. Preferably, this confirmation causes an email to be sent to the data entry system 402, indicating successful completion of the activation process.
FIG. 5 is a diagram showing another exemplary embodiment of the present invention, In this embodiment, a 911 emergency service may be utilized. In this embodiment, a user 502 places a telephone call 504 destined for a 911 emergency service by dialing 911 on a telephone device. The telephone call includes a Session Initiation Protocol (SIP) message that includes the user telephone number that for which 911 emergency service was activated in the process shown in FIG. 4. The telephone call 504 is received at an apparatus included in network 111, which translates the 911 call into a request for a database lookup including the user telephone number in the form of an automatic number identification (ANI), and transmits the request 506 including the ANI to database system 402. Database system 402 looks up the received ANI and retrieves the corresponding PSAP telephone number, which is the telephone number of the PSAP serving the user location that was mapped in the process shown in FIG. 4. In other words, the PSAP selected is based on the physical location of the user placing the call to 911 and the user telephone number is used as a lookup key to retrieve the telephone number of the PSAP from the database. Typically, the telephone number of the PSAP is a physical telephone number on the Public Switched Telephone Network (PSTN). Database system 402 transmits the PSAP telephone number 508 to an apparatus included in network 111, which routes 510 the 911 call 504 from the user 502 to the PSAP 512 using the PSAP telephone number 508. The system included in network 111 may generate a new SIP message including information on the desired call routing and transmit this message to a gateway included in network 111. The gateway, which interfaces network 111 with the PSTN then obtains the call and routes it 510 to PSAP 512 over the PSTN. Call 510 may include the standard information included in a call routed to the PSAP, such as the originating location of the call (the user location), and the ANI of the user device. The user 502 then communicates with PSAP 512 as necessary and PSAP 512 may dispatch an emergency response 514 to the user location.
Thus, the present invention involves receiving calls from geographically arbitrary originating numbers within an area, such as within the well-known North American Numbering Plan (NANP) area, mapping the geographically arbitrary originating number to a geographically significant, unique (and correct for the purpose of resolving an emergency call) PSAP telephone number, and routing the call to that PSAP telephone number. In addition, if a receiving device at the PSAP is equipped to receive location and ANI information, this information can be can be delivered thru the data network to the PSAP.
Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.

## Claims

1. A method for completing an emergency call, comprising:
receiving a call from a location requesting emergency service, the location having a telephone number associated therewith;
obtaining an emergency call center telephone number that handles emergency calls for the location requesting emergency service, said emergency call center telephone number mapped directly to the telephone number of the location requesting emergency service prior to receiving the call from the location requesting emergency service; and
routing the call to the emergency call center using said obtained emergency call center telephone number.

2. The method of claim 1, wherein the emergency call center telephone number is directly mapped to the location telephone number using physical address information prior to receiving the call from the location requesting emergency service.

3. The method of claim 2, wherein the physical address information is geocoded and transmitted to a database that stores the emergency call center telephone number that corresponds to the physical address information.

4. The method of claim 1, wherein the received call further comprises a message that includes the location telephone number.

5. The method of claim 4, wherein the message is a SIP message.

6. The method of claim 1, wherein the call is placed by dialing 911.

7. The method of claim 1, wherein the emergency call center telephone number is a physical telephone number on a switched telephone network.

8. The method of claim 1, wherein the routed call includes the location requesting emergency service.

9. A system for completing an emergency call, comprising:
an intermediate network apparatus connected to a data network and configured to
receive a call from a location requesting emergency service, the location having a telephone number associated therewith, and
obtain an emergency call center telephone number that handles emergency calls for the location requesting emergency service, said emergency call center telephone number mapped directly to the telephone number of the location requesting emergency service prior to receiving the call from the location requesting emergency service; and
a gateway configured to route the call to the emergency call center using said obtained emergency call center telephone number.

10. The system of claim 9, wherein the emergency call center telephone number is directly mapped to the location telephone number using physical address information prior to receiving the call from the location requesting emergency service.

11. The system of claim 10, wherein the physical address information is geocoded and transmitted to a database that stores the emergency call center telephone number that corresponds to the physical address information.

12. The system of claim 9, wherein the received call further comprises a message that includes the location telephone number.

13. The system of claim 12, wherein the message is a SIP message.

14. The system of claim 9, wherein the call is placed by dialing 911.

15. The system of claim 9, wherein the emergency call center telephone number is a physical telephone number on a switched telephone network.

16. The system of claim 9, wherein the routed call includes the location requesting emergency service.

17. A method for completing an emergency call, comprising:
receiving physical address information and a user telephone number;
translating the physical address information into geocoding information;
directly mapping the user telephone number to a corresponding emergency response telephone number based on the geocoding information;
subsequent to the directly mapping, receiving an emergency call including the user telephone number;
transmitting a lookup request corresponding to the emergency call based on the user telephone number;
retrieving the corresponding emergency response telephone number based on the lookup request; and
routing the emergency call and the physical address information to the corresponding emergency response telephone number.

18. The method of claim 17, wherein the step of routing the emergency call includes routing the emergency call simultaneously with the physical address information to the corresponding emergency response telephone number.

19. The method of claim 3, wherein the step of receiving the call includes receiving a first SIP message including the telephone number of the location requesting emergency service.

20. The method of claim 19, wherein the step of routing the call includes generating a second SIP message including the emergency call center telephone number.