# Patent

## Title
Enhanced E911 location information using voice over internet protocol (VoIP)

## Abstract

An E-9-1-1 voice-over-IP (VoIP) solution is provided wherein a 911 call from a wireless VoIP device is routed directly to the correct Public Safety Answer Point (PSAP) via dedicated trunks, together with correct location information and call-back number. VoIP gateways are implemented locally, at least one per LATA, and accept VoIP packetized data inbound, and convert it to standard wireline voice calls. Calls are routed to an IP address at the VoIP gateway, which then egresses the call to a voice port at a selective router. Dedicated voice trunks (CAMA, SS7, FG-D) are installed between each local VoIP gateway and appropriate selective routers. An Automatic Location Identification (ALI) database is provisioned with ESRKs dedicated for VoIP use. TCP/IP circuits may be established between some or all of the various local VoIP gateways.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to VoIP communication carriers. More particularly, it relates to location-based services for the provision of E-9-1-1 emergency services by the VoIP industry.
2. Background of Related Art
911 is a phone number widely recognized as an emergency phone number that is used by emergency dispatch personnel, among other things, to determine a location of a caller. Enhanced 911 (E911) is defined by the transmission of callback number and location information. E911 may be implemented for landline and/or wireless devices.
Some Public Safety Access Points (PSAPs) are not enhanced, and thus do not receive the callback or location information from any phone, landline or wireless.
Voice-Over-Internet Protocol (VoIP) is a technology that emulates a phone call, but instead of using a circuit based system such as the telephone network, utilizes packetized data transmission techniques most notably implemented in the Internet.
As people adopt voice-over-IP (VoIP) technology for routine communications, the inventor herein recognizes that there is a growing need to be able to access E911 services including provision of location information from a VoIP device. The existing E911 infrastructure is built upon copper wire line voice technology and is not compatible with VoIP.
There are at least three VoIP scenarios that require E911 service:

    
    
        1. The VoIP device is physically connected to a static data cable at a “home” address.
        2. The VoIP device is physically connected to a data cable at a location different than its “home” address. For instance, a laptop computer device utilized away from home as a VoIP communication device would be a VoIP ‘visitor’ device as described by this scenario.
        3. The VoIP device is wireleless, physically disconnected from any data cable. In this situation, the VoIP device connects to the VoIP network via cellular or WiFi technology.
    
    


Conventional VoIP voice gateways are typically located in only a few places across the country. Thus, any 911 call originating in a city such as Miami, for example, may initially be routed to the public safety answer point (PSAP) in, e.g., Minneapolis if the VoIP gateway happens to be located in Minneapolis. Moreover, the call will not be “enhanced”. That is, it will not provide any location or callback information to the dispatcher. This problem has been partially resolved as described in FIG. 2.
As shown in FIG. 2, a conventional architecture routes VoIP 911 calls to a designated PSAP. However, such architecture fails to provide “enhanced” service for VoIP devices.
In particular, as shown in Option 1, an IP device 250 utilizing VoIP protocols for voice communications dials 9-1-1. The VoIP device 250 is serviced by a VoIP switch 220 in the VoIP carrier's network. The VoIP switch 220 communicates with a Message Servicing Center (MSC) 230. Using a database that relates the devices callback number or IP address to the owner's address, the MSC 230 can determine which PSAP has jurisdiction for that address. The MSC 230 then communicates back to the VoIP switch 220 a 10-digit telephone number for that PSAP. The VoIP Switch 220 then converts the IP call to TDM and routes the call via the PSTN to the designated PSAP using the provided 10-digit number.
A primary challenge results from the fact that the E911 network is not accessible via the Public Switched Telephone Network (PSTN); all enhanced 911 calls must be routed via dedicated local voice trunks to a selective router that in turn routes the call to the PSAP. Calls routed via the PSTN arrive at the PSAP without callback number or location information. Provision of location information to the PSAP via the PSTN also circumvents specific PSAP hardware (e.g., CAD, GIS) designed to facilitate dispatching of responders and tracking the location of the wireless caller.
There is a need for an architecture and methodology to allow VoIP users all features relating to E911 services enjoyed by non-VoIP users, e.g., call back phone number and location information provided to a public safety answer point (PSAP).
SUMMARY OF THE INVENTION
In accordance with the principles of the present invention, a method and apparatus for routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device comprises provisioning a first local voice-over-Internet Protocol (VoIP) gateway. A first dedicated trunk line is established between the provisioned first local VoIP gateway and a first selective router associated with a first PSAP. An ESRK is importantly associating a specific PSAP to a location of a VoIP device from which the E911 call originates. The E911 call and ESRK are routed to specific PSAPs responsible for receiving E911 calls from the location from which the E911 call originates on the VoIP device.



BRIEF DESCRIPTION OF THE DRAWINGS
Features and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the drawings, in which:
FIG. 1 shows a block diagram of the architecture of the VoIP solution, in accordance with the principles of the present invention.
FIG. 2 shows a conventional architecture for providing 911 service to a VoIP device.



DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The present invention provides an E-9-1-1 voice-over-IP (VoIP) solution, wherein a 911 call from a VoIP device is routed directly to the correct Public Safety Answer Point (PSAP) via dedicated trunks, together with correct location information and call-back number.
In accordance with the present invention, local VoIP gateways are incorporated, and a centralized routing intelligence is implemented, to provide access to the existing E911 infrastructure.
FIG. 1 shows a block diagram of the architecture of the VoIP solution, in accordance with the principles of the present invention. There are two additional options illustrated, in addition to the conventional option shown in FIG. 2.

    
    
        1. Option 2: proposed technology for providing enhanced 911 service from IP devices located at “home” or at “visitor” locations, physically connected to the VoIP network via cable.
        2. Option 3: proposed technology for providing enhanced 911 service from wireless IP devices.
    
    


In particular, as shown in FIG. 1, VoIP gateways 100 are implemented locally, e.g., one within each local access and transport area (LATA). The local VoIP gateways 100 accept VoIP packetized data inbound, and convert it to standard wireline voice calls. Calls are routed to an IP address at the VoIP gateway, which then egresses the call to a voice port at a selective router. Suitable VoIP gateways are otherwise conventionally known and commercially available.
Dedicated voice trunks 107-109 are installed between each local VoIP gateway 100 and appropriate selective routers 150a-150c (referred to collectively herein as selective routers 150). Examples of common voice trunks include Centralized Automatic Message Accounting (CAMA) trunks 107, Signaling System #7 (SS7) voice trunks 108, and/or FG-D trunks 109 are installed between each local VoIP gateway 100 and a respective group of selective routers 150.
The selective routers 150 are provisioned as desired and otherwise conventionally known.
An Automatic Location Identification (ALI) database 190 is included, and is provisioned with Emergency Service Routing Keys (ESRKs) dedicated for VoIP use as desired and otherwise conventionally known.
Transport Control Protocol/Internet Protocol (TCP/IP) data circuits may be installed between various local VoIP gateways 100. For instance, additional IP circuits may be established between the local VoIP gateway(s) of other carriers to handle additional VoIP traffic.
The message flow resulting from a VoIP call from a given IP device, e.g., IP device 352, is now described with reference to FIG. 1.
As a descriptive example, assume a VoIP “E911” call is being placed by VoIP device 352 as shown by “Option 2” from the left side of FIG. 1. The following describes message flow to route that call directly to the correct PSAP, including the provision of location information of the VoIP device 352 to the correct PSAP.
In step 1, a caller using the VoIP device 352 dials “911” on their VoIP device 352. In the given example, the VoIP device 352 provides location information with the E911 call.
In step 2, the VoIP switch 120b servicing that particular VoIP device 352 receives the E911 call, and queries the wireless carrier MSC 130b for routing information. The query to the MSC 130b includes a callback number, and location information (if mobile).
In step 3, the MSC 130b relates location to specific PSAPs. If the location is static, the phone number and location will already be established in the MSC database 130b. If the VoIP device 352 is mobile, the caller provides location information at the time of log-on. This caller information will then accompany the E911 call. In certain scenarios such as even in static situations, the location information may accompany the E911 call.
In step 4, upon determination of the appropriate PSAP to receive the E911 call, the MSC 130b responds with an Emergency Service Routing Key (ESRK), plus IP routing instructions to the VoIP switch 120b. The utilized ESRK is a 10-digit number compatible with the selective router that serves that particular PSAP. ESRKs uniquely identify a specific PSAP. In FIG. 1, only the selective routers 150 compatible with one local VoIP gateway 100 are shown, as are PSAPs 200-206 having dedicated E911 trunks associated with each of those selective routers 150. The person of skill in the art will understand from FIG. 1 that similar local Gateway's will be implemented throughout a large area, e.g., across state lines or even countries, each having associated selective routers, and each selective router having one or more dedicated trunk line to a given one or more PSAPs.
The ESRK provided by the MSC 130b to the VoIP switch 120b is unique to the particular PSAP servicing the location that the wireless VoIP device 352 is calling from. The IP routing instructions provided by the MSC 130b to the VoIP switch 120b identify the IP address of the correct local VoIP gateway in the local access and transport area (LATA) where the compatible selective router exists. For example, it might be the local VoIP gateway 100 shown in FIG. 1, or it might instead be another local VoIP gateway associated with another local area (e.g., another LATA).
In step 5, the VoIP switch 120b routes the VoIP E911 call to the designated VoIP gateway 100. The routed VoIP E911 call includes the ESRK.
In step 6, the VoIP gateway 100 recognizes the ESRK, and selects a corresponding voice egress trunk (e.g., CAMA, SS7 or FG-D) 107-109. The VoIP gateway 100 converts the VoIP data to voice, and egresses the E911 call to the proper selective router 150a, 150b or 150c on the selected trunk 107-109.
In step 7, as in otherwise conventional techniques, upon reaching the selective router 150a, 150b or 150c, the existing E911 infrastructure delivers the E911 call to the proper PSAP 200, 202, 204 or 206 that is assigned to the location that the wireless VoIP device 352 is calling from. Thus, the relevant selective router 150a, 150b or 150c previously provisioned to recognize the ESRK in the ANI field of the CAMA or SS7 voice E911 call, will route the E911 call to the appropriate PSAP 200, 202, 204 or 206.
In step 8, as in otherwise conventional techniques, the PSAP 200, 202, 204 or 206 receives the E911 voice call, and using the ESRK, queries the ALI database 190 for the location of the caller, and for call-back information.
The ALI database 190 steers the ESRK to the appropriate MSC 130b, which in turn responds to the ALI query with the correct location and call-back information. The disclosed ALI query employs otherwise conventional PAM or E2+ protocols.
The sequence of events for Option 1 would be similar as for the above described Option 2, except that the location information would already be stored at the MPC and would not necessarily need to forwarded by the device.
Sequence of events for Option 3 (wireless IP device) would be as follows:
In step 1, a caller using the wireless VoIP device 355 dials “911”.
In step 2, the VoIP switch 120b servicing that particular VoIP device 352 receives the E911 call, and queries the wireless carrier MSC 130b for routing information. The query to the MSC 130b includes a callback number, but no location information.
In step 3, the MSC 130b initiates a GPOSREQ to the Position Determining Equipment (PDE) 400 serving the wireless carrier that provides the wireless coverage for the IP device. A PDE is a position determining device that determines a position, e.g., a latitude and longitude in the wireless Phase 2 world. Many wireless VoIP devices utilize cellular technology, thus positioning equipment used for cellular devices may be utilized for VoIP devices, given the present invention.
The PDE 400, using otherwise conventional techniques, responds with a gposreq response that contains the latitude and longitude of the wireless IP device. The MPC 130b relates location to a specific PSAP.
Subsequent steps in Option 3 are similar to those described with respect to Option 2.
Implementation of E911 for VoIP callers as disclosed herein facilitates the migration of an individual PSAP to a pure VoIP environment, minimizing additional engineering as VoIP systems become more prevalent and revolutionize the telecom industry.
While the invention has been described with reference to the exemplary embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments of the invention without departing from the true spirit and scope of the invention.

## Claims

1. A method of routing an Emergency Service Routing Keys (ESRK) to public safety answer point (PSAP) relating to a call from a VoIP device, comprising:
provisioning a first local voice-over-Internet Protocol (VoIP) gateway; 
establishing a first dedicated trunk line between said provisioned first local VoIP gateway and a first selective router associated with a first PSAP; 
use of an ESRK associating a specific PSAP to a location of said VoIP device from which said E911 call originates; and 
routing said E911 call and ESRK to specific PSAPs responsible for receiving E911 calls from said location from which said E911 call originates on said VoIP device.

2. The method of routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 1, further comprising:
establishing a TCP/IP communication channel between said first local VoIP gateway and to correct antecedent basis second local VoIP gateway.

3. The method of routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 1, further comprising:
receiving a VoIP E911 call from a VoIP device; 
querying a Message Servicing Center (MSC) from a VoIP switch servicing said VoIP device for ESRK information; and 
receiving in response an ESRK.

4. The method of routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 3, further comprising:
querying from said MSC an Automatic Location Identification (ALI) database for said ESRK information relating to an E911 call from said VoIP device.

5. The method of routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 1, wherein:
said VoIP device is a wireless device that uses a Position Determining Equipment (PDE) to determine it's location.

6. Apparatus for routing an Emergency Service Routing Keys (ESRK) to public safety answer point (PSAP) relating to a call from a VoIP device, comprising:
means for provisioning a first local voice-over-Internet Protocol (VoIP) gateway; 
means for establishing a first dedicated trunk line between said provisioned first local VoIP gateway and a first selective router associated with a first PSAP; 
means for using an ESRK associating a specific PSAP to a location of said VoIP device from which said E911 call originates; and 
means for routing said E911 call and ESRK to specific PSAPs responsible for receiving E911 calls from said location from which said E911 call originates on said VoIP device.

7. The apparatus for routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 6, further comprising:
means for establishing a TCP/IP communication channel between said first local VoIP gateway and to correct antecedent basis second local VoIP gateway.

8. The apparatus for routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 6, further comprising:
means for receiving a VoIP E911 call from a VoIP device; 
means for querying a Message Servicing Center (MSC) from a VoIP switch servicing said VoIP device for ESRK information; and 
means for receiving in response an ESRK.

9. The apparatus for routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 8, further comprising:
means for querying from said MSC an Automatic Location Identification (ALI) database for said ESRK information relating to an E911 call from said VoIP device.

10. The apparatus for routing an ESRK to public safety answer point (PSAP) relating to a call from a VoIP device according to claim 6, wherein:
said VoIP device is a wireless device that uses a Position Determining Equipment (PDE) to determine it's location.