NG 911 Project

Wonsang Song, Jong Yul Kim, and Henning Schulzrinne

Internet Real-Time Lab, Columbia University

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Overview

• Project goals

• Four phases of an emergency call1) Call identification

2) Determining caller location

3) Routing to call center

4) Call presentation

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Project Goals

• Develop a prototype system that routes emergency calls over SIP based VoIP networks.

• Implement requirements for IP-based PSAP

• Provide opportunities to enhance 911 system:– Multimedia (audio, video, text)– Data delivery (floor plan, CPR how-to)– Language-based routing

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Four Phases of Emergency Calling

Phase 1 Phase 2 Phase 3 Phase 4

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Phase 1 : Identifying Emergency Calls

• Emergency URI– sip:sos@irt.cs.columbia.edu

• Identification by number– (911, 112) -> sip:sos@irt.cs.columbia.edu

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Phase 2 : Determining Caller Location

• Different types of callers– stationary, nomadic, or mobile

• Different types of solution

CDP DHCP GPS Manual Entry

Merits Cisco devices are ubiquitous

Less burden for administrators than DHCP

DHCP is ubiquitous

Applicable to both SIP UA and SIP proxy

Delivers precise location

No work for administrators

Is always a backup method

Drawbacks Only works with Cisco switches and access points

Administrators have to enter switch – location mapping

No good for wireless connections

Administrators have to enter machine – location mapping for each machine

GPS does not work indoors or when a significant portion of the sky is blocked from view.

No guarantee of timely update

Prone to human error

Useful Situation

In organizations that use Cisco devices

In organizations where computers are fixed in one place

Outdoors When all else fails

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Phase 3 : Routing to Correct PSAP

• Which PSAP should the call go to?– Usually to the PSAP that covers the area– Sometimes to a backup PSAP– If no location, then ‘default’ PSAP

• PSAP determination– DNS-SOS– LUMP : Location-to-URL Mapping Protocol

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Phase 4 : Call Presentation in PSAP

Call Taker 1

Call Taker 2

Call Taker n

Hospital Police Fire Envinsa Server

HTTP SOAPTelephone #

Location Info

psap@domainw/location

Controller (psapd)

Policy

Conference Mixer

selectavailable calltaker

createconference

INVITE toconference

joinconference

REFER PoliceTo conference

joinconference

(1)

(3)(2)

(4)

(5)

(6a)

(6b)

(8)

(7)

INVITE toconference

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Screenshot of a call taker

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Thank you!

• Question?