Post on 20-Dec-2015
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?