Patent Application
20070298765
In a first embodiment, an emergency call (e.g., 911 call, alarm company call) forwarded by a telematics call center is routed over the switched PSTN to a Voice Over Internet Protocol (VoIP) call server, where the switched call is converted to a packetized IP call for presentation to an emergency services gateway (ESGW) which in turn routes the call to a selective router, gaining access to the Enhanced 911 network. Call routing information is provided using a VoIP positioning center (VPC), which determines the appropriate ESGW and assigns a related Emergency Services Query Key (ESQK).
In a later embodiment, the VoIP network of ESGWs and VPC is used to route wireless emergency services routing keys (ESRKs) to an enhanced E911 network of a public service access point (PSAP) using packetized VoIP data.
Voice Over IP (VoIP) is a technology that has been developed as an alternative telephony technology to the conventional telephony service (e.g. PSTN). VoIP takes advantage of high speed Internet data packet networks, and is able to provide low cost telephony services to end users. VoIP technology 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.
Voice-Over-Internet Protocol (VoIP) 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.
VoIP phone calls are routed to a VoIP call server, from which they are passed on to their destination VoIP device. Conventional VoIP call servers (i.e., soft switches) are typically located in only a few places across the country. A soft switch is a programmable network switch that can process the signaling for all types of packet protocols. Softswitches can support, e.g., IP, DSL, ATM and frame relay. In many cases, VoIP calls must interface with traditional TDM calls. This is accomplished via media gateways (protocol converters) that integrate SS7 telephone signaling with packet networks.
Because VoIP is Internet Protocol (IP) based, call related information such as CallerID type services may not be available or accurate. This is particularly true of caller location data during emergency calls.
The present invention applies VoIP technology in lieu of the switched telephone connectivity of the PSTN to route calls to a media gateway/VoIP call server 112. The switched call is converted into a packetized call using Internet Protocol (IP), and is routed via the internet to the ESGW 114 closest to the appropriate selective router for the destination PSAP. The ESGW converts the packetized IP data back into traditional TDM, and routes the call to the intended selective router 116 via dedicated TDM trunks, where it enters the E911 network. A selective router is the node in an emergency services network that performs enhanced call routing for 911 calls.
An example will be used to further illustrate the inventive architecture. In this example, a telematics unit 101 within a car dials 911. The 911 call is serviced by a cell site of a service provider, which includes a given mobile servicing center (MSC) 102. The MSC 102 forwards the 911 call on to its relevant telematics call center 104 via the PSTN. The telematics call center 104 may be, e.g., an ONSTAR™ call center, and may be located anywhere in the country or anywhere in the world.
The operator at the telematics call center 104 that handles the 911 call of its own subscriber obtains the nature of the call, as well as the identity and location of the 911 caller. The identity and location of the 911 call from the subscriber is most often received by the call center 104 over the open phone line to their subscriber. Equipment to receive the exact location of the subscriber is expensive, but necessary only at the centralized telematics call center. The thousands of PSAPs in the country do not have the same equipment, as it would be prohibitively expensive.
Based on the current location of the 911 caller, the operator performs a query of a telematics PSAP database 106 to determine a local PSAP physically responsible for that location, as well as a unique 10-digit phone number to access the Enhanced 911 network of that PSAP.
The operator at the telematics call center 104 handling the 911 call forwards the emergency call to a given media gateway/VoIP call server 112 by dialing the designated 10-digit number for that PSAP
To determine the appropriate PSAP and ESGW, the VoIP call server 112 queries a VoIP positioning center (VPC) 130. Using the 10-digit phone number dialed by the call center operator 104, the VPC queries the database 134 to determine the corresponding PSAP. The VPC then assigns an Emergency Services Query Key (ESQK) to the call and relays this routing key back to the VoIP Call Server 112.
The VoIP call server 112 passes the 911 emergency call on to an emergency service gateway (ESGW) 114, which in turn passes the 911 emergency call on to the desired PSAP 118. An ESGW resides in a VoIP service provider's network, and is responsible for integrating the session initiation protocol (SIP) network with the emergency services network (TDM). An ESGW 114 network includes dedicated voice trunks to selective routers in the Enhanced 911 (E911) network for any/all PSAPs being served (ideally a national network). The ESGW 114 routes 911 calls to the appropriate selective router, based on the ESRN/ESQK it receives.
The selective router 116 is provisioned with emergency services query keys (ESQKs) with ALI steering. (The ESQK is a digit string that uniquely identifies an ongoing emergency services call and is used to correlate the emergency services call with the associated data messages. It may also identify an emergency services zone and may be used to route the call through the network. The ESQK is similar to an ESRK in wireless E911 networks.)
A subscriber location database (SLDB) 134 is also provisioned. Preferably the SLDB 134 is configured so that no modifications are required to the core conventional existing VoIP E9-1-1 network. The SLDB 134 is used to relate a Session Initiation Protocol (SIP) Universal Resource Identifier (URI) or a telephone number to a PSAP.
In the given embodiments the SLDB 134 includes a listing of a series of “subscribers”, in which each subscriber is really a specific PSAP with a designated 1-900-xxx-yyyy phone number. Note that the phone number does not need to be a 1-900 number as this is used as an example only. This is also a useful technique for billing the call center for this service.
In the disclosed embodiments, the address of this “subscriber” is the latitude/longitude (lat/lon) of a centroid of the jurisdiction of the relevant PSAP. Alternatively, in databases that use tables in lieu of GIS for routing determination, the address of the “subscriber” can be any valid address within the jurisdiction of the PSAP.
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The 911 call may be placed using an SOS or similar single-press button located in a car for use in emergency situations, automatically in the event of an accident, etc. Alternatively, the phone user may simply dial 911 in a manual cell phone call from a mobile phone, either integrated into a vehicle or entirely separate from a vehicle.
In step 2, a wireless MSC 102 routes the incoming emergency call to a telematics call center 104 (e.g., an ONSTAR™ or TeleAid™ call center). In the given example this routing includes use of the PSTN 110, though this need not be the case in all applications.
The call taker at the call center 104 who receives the 911 call from the caller 101 determines that this is an emergency call that must be referred to the local 911 PSAP.
Thus, in step 3, the telematics call taker queries an existing telematics PSAP database 106 to determine the correct PSAP to which the call should be routed. Of course, to save time step 3 may be performed simultaneous with, or even prior to, the call taker's determination that the call from the mobile user 101 is an emergency call.
In step 4, a telematics dispatcher dials (could be the same person and/or equipment as the call taker) a NPA-xxx-yyyy number designated for the determined PSAP. For instance, the call taker at the call center 104 then dials 1-900-xxx-yyyy, a designated number for that PSAP 118, and prepares to conduct a conference call with the caller 101 and the PSAP 118.
The call is then routed, via the PSTN 110, to a designated VoIP call server 112 (alternatively referred to as a media gateway). The media gateway and the VoIP call server may be two distinct functions co-located in the same unit, as in the present embodiment. The media gateway converts TDM to IP. The VoIP call server routes the resulting IP calls much like a traditional telephone switch routes a TDM call.
The VoIP call server 112 receives the ANI (caller ID) of the call center. The VoIP media gateway 112 reformats the call from time division multiplex (TDM) or code division multiplexed (CDM) into session initiation protocol (SIP). The VoIP Call Server rearranges the dialed digits, putting the DID that was dialed in step iii (e.g., 1-900-xxx-yyyy) in the FROM field and putting the ANI of the call center into the Just-in-Time callback number (JIT CBN) field within the P-Asserted Identity in the SIP Invite. (Session initiation protocol (SIP) is an IP-based protocol defined in IETF RFCs 3261 and 2543, the entirety of which are expressly incorporated herein by reference. SIP is one of two dominant messaging protocols used by the VoIP industry.
Importantly, the VoIP Media Gateway/call server 112 converts the TDM or CDM protocol of the incoming switched network phone call to packet data using session initiation protocol (SIP), and vice versa, meaning that packetized VoIP information coming from a relevant PSAP is converted into a switched connection with the 911 caller, terminated at the VoIP call server 112.
In step 5, the VoIP call server 112.forwards the 911 call to the VPC 130 as a VoIP call. The Invite is received by the VPC 130 for call routing instructions.
The VPC 130 is an application that determines the appropriate PSAP, based on the location of the 911 caller 101, returns associated routing instructions to the VoIP network, and provides the call center's identity and the callback number to the PSAP through the automatic location identification (ALI). (An ALI is a database that relates a specific telephone number to an address. This database accepts a PSAP query with a telephone number and responds with an address. In the case of an ESQK, the ALI database steers (redirects) the query to the appropriate VoIP positioning center and steers the response back to the querying PSAP).
A SIP Invite command may be used for the query from the Call Server 112 to the VPC 130. The disclosed SIP Invite command preferably includes the following parameters:
In step 6, the VoIP positioning center 132 queries an ERDB (SLDB) 134 for call routing instructions based upon the dialed NPA-xxx-yyyy number. The ERDB 134 relates the dialed number to the address of that phone number (lat/lon of the PSAP jurisdictional centroid) and determines the appropriate PSAP to receive the call. Within the ERDB 134, each phone number corresponds to a different PSAP.
In step 7, the ERDB 134 responds to the VPC 130 with the identity of the appropriate PSAP to serve the caller 101. The VPC 130 assigns an ESQK and emergency services routing number (ESRN) to the call and stages an ALI record. The ESRN is a 10-digit number that specifies the selective router to be used to route a call. The ALI record contains the phone number of the call center 104, based upon the ANI that accompanied the call. If the call center 104 is capable of sending the ANI of the actual end user, then this can be staged in the VPC ALI record.
Further call processing is otherwise per the conventional NENA i2 VoIP standard:
For instance, in step 8, the VoIP positioning center 130 assigns an emergency services query key (ESQK) appropriate to that PSAP, and stages a record with the call center call back number (CBN) and call center company ID.
The VoIP positioning center 130 responds to the VoIP call server 112 with the ESQK, emergency services routing number (ESRN), and last routing option (LRO). (The LRO is routing information sent by the VPC 130 that provides a “last chance” destination for a call, for example the contingency routing number (CRN) or a routing number associated with a national call center.
In step 9, the VoIP call server 112 uses the ESRN to route the call to the correct emergency services gateway (ESGW) 114.
The VoIP call server 112 uses the received ESRN to determine the appropriate ESGW 114 and routes the call appropriately to the correct emergency services gateway (ESGW) 114. The ESGW 114 uses the ESRN to determine the appropriate selective router 116. For simplicity and clarity of description, only one ESGW 114 and one selective router 116 are pictured in
In step 10, the ESGW 114 performs media conversion by converting the SIP protocol (and vice versa in the opposite communication direction), and uses the ESRN to route the call to the correct selective router 116, along with the ESQK.
In step 11, the selective router 116 routes the ESQK to the PSAP 118.
In step 12, the PSAP 118 queries the automatic location identification (ALI) database 120 using the ESQK.
In step 13, the ALI database 120 steers the query to the VoIP positioning center (VPC) 130, per previously provisioned steering tables. The VPC 130 responds with a staged record that includes the callback number (CBN) and call center company ID. In the preferred embodiments, no latitude/longitude (lat/lon) is sent in the ALI record, although such data could be forwarded if it is available.
In step 14, the ALI database 120 forwards the callback number (CBN) and call center ID to the requesting PSAP 118.
The embodiments of
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The VoIP call server 112 queries a voice positioning center (VPC) 132 for routing instructions, using existing E5 message formatting as described in standard J-Std 036. The VPC 132 extracts location information in the E5 message, then uses this location information, plus existing functionality traditional to wireless MPCs, to determine the appropriately designated PSAP 118 to receive the 911 call.
Importantly, the VPC 132 assigns an ESRK, ESRN and CRN, and responds with this information to the VoIP Call Server 112. The VPC 132 also stages a record in a database that correlates the ESRK with the caller's phone number and location.
The VoIP call server 112 uses the ESRN to determine the appropriate ESGW 114 and routes the 911 call accordingly.
The ESGW 114 uses the ESRK to determine the correct selective router trunk and converts the call from IP protocol to SS7 or CAMA TDM protocol. The ESGW 114 then routes the call accordingly.
The remaining portion of the 911 call routing process is performed in accordance with existing art. For instance, the selective router 116 uses the ESRK to determine the appropriately designated PSAP 118 and routes the 911 call accordingly.
The PSAP 118 queries the automatic location identification (ALI) database 120 for caller ALI data. The ALI database 120, recognizing the ESRK, steers the query to the VPC 132, which responds with the previously staged record. The ALI database 120 or the wireless MPC 102 assigns a class of service (COS) to the call based upon the ESRK.
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The embodiments of
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.
