Internet Real-Time Lab, Columbia University

Next Generation 9-1-1 Project

Jong Yul Kim, Wonsang Song, and Henning Schulzrinne

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Overview

• Project Introduction

• Architecture and implementation

• References

• Demo

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Growth of VoIP Subscribers

• Global Subscribers– 16 million in 2005– 62% year-over-year

subscriber growth rate in 2005

– 55 million by 2009

Numbers from instat.com

Released on Jan. 31, 2006

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But there were problems…

• VoIP service did not connect to 911; • VoIP service rang to the administrative line of the public safety answering

point (PSAP), which is not often staffed after hours, and is usually not staffed by trained 911 operators;

• VoIP service rang to the correct line of the PSAP, but did not automatically include the consumer’s phone number and/or location information.

• Consumer must provide certain information (such as location information) in order for the VoIP provider to set up 911 service, but failed to do so

• Consumer moved VoIP service to another location (the phone number can be used anywhere the customer has a broadband connection) but the VoIP service did not reflect the new address;

• VoIP service did not work during a power outage; • VoIP service did not work when the broadband connection (cable modem

or DSL) went down or was congested.

Taken from http://www.fcc.gov/cgb/consumerfacts/voip911.html

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Three Fundamental Problems

1. Where is the caller?

2. To which PSAP should the call go to?

3. How to identify the emergency call?

Problems 2 and 3 arise from problem 1.

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• 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, medical information)– Delivering video (CPR how-to)– Load balancing and redundancy – Location delivery (location with forwarded, transferred calls)

Project Goals

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A Collaborative Effort

• Funding– U.S. Department of Commerce

• National Telecommunications and Information Administration (NTIA)• Requirements

– National Emergency Number Association (NENA)• Software Development

– Columbia University• Deployment and Testing

– Texas A&M University• Standardization

– IETF ECRIT, GEOPRIV WG• Contributions

– States of Texas and Virginia 911 offices– Corporations like Cisco, Nortel, MapInfo, etc.

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The Big Picture from NENA

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911112

sip:psap@domain2w/location

geo location

POTS/Wireless Network

SIP UA

911

sip:psap@domain2with location

GeoLynx /Google Maps

DHCP Server

civil location

PSAP Info

Location

Mapping Server

geo locationcivil location

psapd

3PCC Controller

IP Gateway

Local SIP Proxy

PSAP

PSAP SIP Proxy

sip:psap@domain2with location

sip:rep@domain2with location

urn:service:sosw/out location

LIS

Location InfoLocation

key

Our Much Simpler Picture

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Phase 1 Phase 2 Phase 3 Phase 4

Determine Location

Present Call to

Calltaker

Route to Correct PSAP

IdentifyEmergencyCalls

Four Phases of Emergency Calls

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911112

sip:psap@domain2w/location

geo location

POTS/Wireless Network

SIP UA

911

sip:psap@domain2with location

GeoLynx /Google Maps

DHCP Server

civil location

PSAP Info

Location

Mapping Server

geo locationcivil location

psapd

3PCC Controller

IP Gateway

Local SIP Proxy

PSAP

PSAP SIP Proxy

sip:psap@domain2with location

sip:rep@domain2with location

urn:service:sosw/out location

LIS

Location InfoLocation

key

phase1

phase2

phase3 phase4phase3

phase1

System Components

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• Purpose– To get emergency dial strings (Phase2)– To resolve the correct PSAP URL (Phase3)– To present the caller’s location on the call taker’s screen

using mapping software (Phase4)

Phase1: Determining Location

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Phase1: Determining Location (cont’d)

• Problem– User can be stationary, nomadic or mobile

• Solution– Apply different methods for different situations– DHCP, CDP (LLDP-MED), SkyHook (Wireless AP Location

Database), GPS, and Manual Entry– The result is either civic address or geospatial coordinates.– Location will be included in the body of the INVITE request

as PIDF-LO object.

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DHCP for Location

• Mainly for stationary users• We modified ISC’s dhcpd to generate location information• Use MAC address to get location information

DHCP Server

or

request

response

DHCPINFORM[MAC=00:11:20:9d:a0:03]

DHCPACK[option=0:US:1:NY:2:NEW YORK:3:NEW YORK:6:AMSTERDAM:19:1214]

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LLDP-MED for Location

• Mainly for stationary and nomadic users• Link Layer Discovery Protocol – Media Endpoint Discovery(Layer2)• Switch broadcasts location data periodically.• A Switch covers a floor, a port leads to a jack in a room

-> room-level accuracy

Segment from switch 2/port 5

Switch 2

Path of CDP advertisement

SIP UA

InvokecdpCap

cdpCap listens to advertisements

Send switch/port information

Physical location

Switch/port

Location DB

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SkyHook for Location

Taken from http://www.skyhookwireless.com

• Mainly for nomadic, mobile users• Wireless device receives signals from Wi-Fi sites in range• Skyhook compares signals to its database of geographically known

locations • Location data is used to direct safety services

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INVITE urn:service:sos SIP/2.0

To: urn:service:sosCall-ID: 763782461@192.168.1.106Via: SIP/2.0/TCP 192.168.1.106:4064;rportContent-Type: multipart/mixed; boundaryFrom: sip:caller@irt.cs.columbia.eduContact: <sip:eddie@160.39.54.70:5060>CSeq: 1 INVITEContent-Length: 1379

------ =_ZGY1NTFlZDJkMDkxY2FkMTIxMWI2MzIzNjE1M2U0OTY=MIME-Version: 1.0content-Type: application/sdpContent-Transfer-Encoding: 8bit

v=0o=eddie 1127764654 1127764654 IN IP4 192.168.1.106s=SIPC Callc=IN IP4 160.39.54.70t=0 0m=audio 10000 RTP/AVP 0 3m=video 20000 RTP 31

SDP

header fields

request line ------- =_ZGY1NTFlZDJkMDkxY2FkMTIxMWI2MzIzNjE1M2U0OTY=MIME-Version: 1.0Content-Type: application/pidf+xmlContent-Transfer-Encoding: 8bit

<?xml version="1.0" encoding="ISO-8859-1"?><presence xmlns="urn:ietf:params:xml:ns:pidf" xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10" xmlns:cl=" urn:ietf:params:xml:ns:pidf:geopriv10:civilLoc" xmlns:gml="urn:opengis:specification:gml:schema-xsd:feature:v3.0" entity="sip:calltaker_ny2@irt.cs.columbia.edu"> <tuple id="28185"> <status> <gp:geopriv> <gp:location-info> <cl:civilAddress> <cl:country>us</cl:country> <cl:A1>ny</cl:A1> <cl:A2>new york</cl:A2> <cl:A3>new york</cl:A3> <cl:A6>amsterdam</cl:A6> <cl:HNO>1214</cl:HNO> </cl:civilAddress> </gp:location-info> <gp:method>Manual</gp:method> </gp:geopriv> </status> <contact priority="0.8">sip:eddie@160.39.54.70:5060</contact> <timestamp>2005-09-26T15:57:34-04:00</timestamp> </tuple></presence>------- =_ZGY1NTFlZDJkMDkxY2FkMTIxMWI2MzIzNjE1M2U0OTY=--

PIDF-LO

Location Info inside a SIP message

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• Purpose– For UA : To send caller’s location information– For Proxies: To handle the emergency call specially

• Problem– Different emergency dial strings

• different in countries (e.g., 911 for North America, 112 for Europe)• some countries uses separate numbers for ambulance/police/fire

– Required to support both home and visited emergency dial strings• e.g., for an American traveler who is visiting Europe, both 911 and 112

should be recognized as emergency

Phase2: Identifying SOS

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• Use Emergency Services URN(instead of emergency numbers)

– Service URN identifies a generic service, not a specific resource

– Examples of emergency services URN:• urn:service:sos• urn:service:sos.ambulance• urn:service:sos.fire• urn:service:sos.police

– Can be used in request URI and To header.– Will be resolved into PSAP URL in phase 3

Phase2: Identifying SOS (cont’d)

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Phase2: Identifying SOS (cont’d)

• What if a user dials an emergency number?

– User can set his/her home country through configuration.

– In initial time, UA gets the home emergency dial strings using mapping protocols.

– Whenever current location is changed, UA gets the visited emergency dial strings using mapping protocols.

– UA keeps all emergency dial strings in the local dial planse.g., [911 -> urn:service:sos]

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• 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– mapping problem:

– Work in progress for standardization of LoST

( LoST = A Location-to-Service Translation Protocol )

Caller’s location

Service identifier

(urn:service:sos)

+Service provider

(PSAP URL)

Phase3: Routing to Correct PSAP

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• Translates a service identifier and location information to {PSAP URL & emergency dial-string}

• Supports both civic and geo location information• Uses web service (SOAP base) as underlying protocol

LoST Server

req

ues

tresp

on

se

LoST (Location-to-Service Translation)

<mapping> <request> <operation>recurse</operation> <service>urn:service:sos</service> <gp:location-info> <cl:civicAddress> <cl:country>US</cl:country> <cl:A1>NY</cl:A1> <cl:A3>New York</cl:A3> <cl:A6>Amsterdam</cl:A6> <cl:HNO>1214</cl:HNO> </cl:civicAddress> </gp:location-info> </request> </mapping>

<mapping> <response expires="2006-03-09T01:53:33.396Z"> <service>urn:service:sos</service> <displayName>New York City PSAP</displayName> <uri>sip:psap_ny@irt.cs.columbia.edu</uri> <civicMatch> <gp:location-info> <cl:civicAddress> <cl:country>US</cl:country> <cl:A1>NY</cl:A1> <cl:A3>New York</cl:A3> <cl:A6>Amsterdam</cl:A6> <cl:HNO>1214</cl:HNO> </cl:civicAddress> </gp:location-info> </civicMatch> <dialstring>911</dialstring> </response> </mapping>

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Call Taker 1

Call Taker 2

Call Taker n

Hospital Police Fire

Controller (psapd)

Policy

Conference Mixer

select available call taker

(2) create conference

(3) INVITE to conference

(4)

(5) join conference

INVITE to conference

(7)

join conference

(8)

(1) psap@domain w/location

(6)

REFER police to conference

Phase4: Call Presentation in PSAP

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Calltaker’s Screen

• SIPc as SIP User Agent• Location Mapping software to display caller’s location

– Geolynx

– Google Maps

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Web Interface

• Manage PSAP systems• Show call logs, details, incident information

and statistics

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LoST Server

SIP proxy call takerSOS caller

(1) Location

Location + Service Identifier

(2)

PSAP URL + emergency dial-string

(3)

INVITE PSAP URLTo: urn:service:sos

<Location>

(5)INVITE PSAP URLTo: urn:service:sos

<Location>

(6)(4)

dial emergency dial-string

or

push emergency button

All Together Now

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• Related Websites– ng911.tamu.edu– www.nena.org– www.ietf-ecrit.org

• Standards and Internet Drafts– SIP: Session initiation protocol, RFC 3261– Requirements for Emergency Context Resolution with Internet

Technologies, draft-ietf-ecrit-requirements-04– Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for

Civic Addresses Configuration Information, draft-ietf-geopriv-dhcp-civil-07– Dynamic Host Configuration Protocol Option for Coordinate-based

Location Configuration Information, RFC 3825– A Presence-based GEOPRIV Location Object Format, RFC 4119– A Uniform Resource Name (URN) for Services, draft-ietf-ecrit-service-

urn-01– LoST: A Location-to-Service Translation Protocol, draft-hardie-ecrit-lost-

00– Best current practices for third party call control (3pcc) in the session

initiation protocol (SIP), RFC 3725

References

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Thank you!

Please join us for a demo of the prototype system