Next Generation 9-1-1 (NG9-1-1) is an IP/SIP-based emergency communication system proposed by the National Emergency Number Association (NENA). It provides media convergence and data integration that is not possible with the current emergency communication system. For example, it is not possible to send a picture or video to the call taker using the current system, but NG9-1-1 is designed to allow such multimedia communications. Also, additional data such as floor plans, health records, or telematics data can be delivered to the call taker when they are needed. The system incorporates location determination, call routing and Public Safety Answering Point (PSAP) infrastructure.
Phase 1 : Summer 2005 ~ Spring 2007
We designed and implemented the basic architecture of NG9-1-1 and its components. We worked on call flow, location-based call routing, and multimedia support.
- NG9-1-1 Basic Architecture
The technical challenges were how to determine emergency calls and how to route calls to the appropriate PSAP. We solved the former problem by defining an emergency service URN and using it in the SIP request-URI and SIP To header field as an identifier of the emergency call. Location-to-Service Translation Protocol (LoST) was proposed and implemented for the routing problem.
Phase 2 : Fall 2007 ~ Summer 2008
With the prototype developed in phase 1, we built a proof-of-concept system for the U.S. Department of Transportation. Integration of different origination networks and supportive/supplemental data was the main goal of this project. The current user interface of the call taker software also came out of this project.
- Call taker software
In the POC, different call originations such as a hardware VoIP phone, a laptop with a VoIP software, a cellular phone, and a simulated telematics device were used to showcase the ability of integration. Supportive data such as a call type or business rules of the Emergency Services IP Network (ESInet) used to route calls to the PSAP as well as the caller's location information.
Phase 3 : Fall 2008 ~ Spring 2009
The primary goal of this phase was the integration of text communication with the NG9-1-1 system. We evaluated various architectural models for both instant messaging (IM) and short messaging service (SMS). One of the models was chosen and implemented as a prototype.
In the case of IM network, one problem is that most popular IM protocols are proprietary and therefore incompatible with the NG9-1-1 system. Thus, we proposed a SIP-based model of integration. Another problem is consistent delivery of multiple messages within a session to the same call taker. We solved this problem by implementing state-keeping mechanisms in three different components within the NG9-1-1 architecture. In the SMS network, there are three problems: location conveyance, SIP conversion, and consistent delivery of multiple messages within a session to the same call taker. We solved the first problem by sending the location information and the user's message in one unit. We introduced an SMS gateway to solve the second problem. To solve the consistent message delivery problem, we implemented state-keeping mechanisms similar to the one used in the IM network.
Phase 4 : Summer 2009 ~
Using the prototype as a testbed, we are planning to study the reliability of SIP-based emergency communication systems. We also want to invent a distributed and collaborated location determination technique. We plan to prove the accuracy of the new technique using user mobility model.
This material is based upon work supported by the National Science Foundation under Grants No. 0751094. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.