NG911 - Next-Generation Emergency Calling

1
NG911 - Next-Generation Emergency Calling

• Henning Schulzrinne
• (with Jong Yul Kim, Wonsang Song, Anshuman Rawat,
  Matthew Mintz-Habib, Amrita Rajagopal and Xiaotao
  Wu)
• Dept. of Computer Science
• Columbia University

2
Introduction

• Emergency calling is a necessary part of consumer
  voice service
• citizen calls PSAP (public safety answering
  point) for assistance
• Existing solutions are insufficient
• may deliver call to wrong PSAP
• particularly for nomadic and mobile users
• may not deliver location to PSAP
• makes it difficult to move call information
  around
• e.g., call location to first responder
• voice only ( TDD)

3
VoIP emergency communications
emergency call
dispatch
emergency alert (inverse 911)
civic coordination
4
Components of emergency calling
now
transition
all IP
Contact well-known number or identifier
112 911
112 911
dial 112, 911 ?urnservicesos
Route call to location-appropriate PSAP
selective router
VPC
DNS
Deliver precise location to call taker to
dispatch emergency help
phone number ? location (ALI lookup)
in-band ? key ? location
in-band
5
What makes VoIP 112/911 hard?
POTS PSTN-emulation VoIP end-to-end VoIP
(landline) phone number limited to limited area landline phone number anywhere in US (cf. German 180) no phone number or phone number anywhere around the world
regional carrier national or continent-wide carrier enterprise carrier or anybody with a peer-to-peer device
voice provider line provider ( business relationship) voice provider ? ISP voice provider ? ISP
national protocols and call routing probably North America EU international protocols and routing
location line location mostly residential or small business stationary, nomadic, wireless
6
The core problem
Voice Service Provider (VSP) sees emergency
call but does not know caller location
ISP/IAP knows user location but does not handle
call
7
Staged deployment

• 6,134 PSAPs in North America
• average 2-3 active call takers each
• some serve town, some large parts of a state
• only 30 of PSAPs can receive geo coordinates
• 30-40 may be voice only
• many using 1970s telecom technology
• CAMA (operator) trunks
• limited to delivering 8 (regional) or 10 digits
  (national) of information
• already facing pressure from supporting cellular
  services
• Phase I (cell tower and face) and Phase II
  (caller geo location)
• EU smaller number of PSAPs, but often without
  location delivery

8
Components

• Location determination
• Call identification --gt service URNs
• Call routing --gt LoST
• PSAP functionality
• IVR, logging, multimedia conferencing,

LoST (public)
LoST (private)
ESN (county, state, )
PSAP
PSAP
Internet
9
More than pain

• Multimedia from the caller
• video capture from cell phones
• video for sign language
• text messaging and real-time text for the deaf
• Data delivery
• caller data floor plan, hazmat data, medical
  alerts
• measurement data input automobile crash data,
  EKGs,
• Delivering video to the caller
• e.g., CPR training
• Load balancing and redundancy
• currently only limited secondary PSAP
• VoIP can transfer overload calls anywhere
• Location delivery
• carry location with forwarded and transferred
  calls
• multiple location objects (civic geo)

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IETF ECRIT working group

• Emergency Contact Resolution with Internet
  Technologies
• Solve four major pieces of the puzzle
• location conveyance (with SIPPING GEOPRIV)
• emergency call identification
• mapping geo and civic caller locations to PSAP
• discovery of local and visited emergency dial
  string
• Not solving
• location discovery
• inter-PSAP communication and coordination
• citizen notification
• Current status
• finishing general and security requirements
• tentative agreement on mapping protocol and
  identifier
• later, to work on overall architecture and UA
  requirements

11
Service URN

• Idea Identifiers to denote emergency calls
• and other generic (communication) services
• Described in draft-ietf-ecrit-service-urn-05
  (passed WGLC sent to the IESG)
• Document defines the following emergency service
  identifiers
• sos General emergency
  services
• sos.animal-control Animal control
• sos.fire Fire service
• sos.gas Gas leaks and gas
  emergencies
• sos.marine Maritime search and rescue
• sos.mountain Mountain rescue
• sos.physician Physician referral service
• sos.poison Poison control center
• sos.police Police, law enforcement

12
counseling services
urnservicecounseling Generic counseling service (call center)
counseling.children run-aways, child abuse
counselingmental-health diagnostic, treatment, and preventive care mental health
counselingsuicide suicide prevention hotline
13
Services under discussion

• 211 (social service referral), 311
  (non-emergency government services)
• Emergency services (first responders)
• used by PSAP, not civilians
• e.g., urnserviceespolice
• Non-emergency commercial services
• urnservicerestaurant.italian
• urnservicetransportation.taxi

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UA recognition UA resolution
location information
mapping
mapping may recurse
DHCP LLDP-MED
9-1-1 (dial string)
leonianj.gov
INVITE urnservicesos To urnservicesos Route
sipfire_at_leonianj.gov ltlocationgt
INVITE urnservicesos To urnservicesos Route
sippsap_at_leonianj.gov ltlocationgt
identification TBD
15
UA recognition proxy resolution
mapping
9-1-1
(outbound proxy) provider.com
INVITE urnservicesos To urnservicesos ltlocat
iongt
INVITE urnservicesos To urnservicesos Route
sippsap_at_leonianj.gov ltlocationgt
16
UA recognition proxy resolution(proxy location
determination)
mapping
9-1-1
provider.com
INVITE sippsap_at_leonianj.gov To
urnservicesos Geolocation ltlocationgt
INVITE urnservicesos To urnservicesos
17
Proxy recognition proxy resolution
mapping
9-1-1
provider.com
INVITE urnservicesos To sip911_at_provider.comus
erphone Geolocation ltlocationgt Route
sippsap_at_leonianj.gov
INVITE sip911_at_provider.comuserphone To
sip911_at_provider.comuserphone
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Finding the correct PSAP

• Which PSAP should the e-call go to?
• Usually to the PSAP that serves the geographic
  area
• Sometimes to a backup PSAP
• If no location, then default PSAP

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LoST functionality

• Satisfies the requirements (draft-ietf-ecrit-requi
  rements) for mapping protocols
• Civic as well as geospatial queries
• civic address validation
• Recursive and iterative resolution
• Fully distributed and hierarchical deployment
• can be split by any geographic or civic boundary
• same civic region can span multiple LoST servers
• Indicates errors in civic location data ?
  debugging
• but provides best-effort resolution
• Supports overlapping service regions

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LoST Properties

• Minimizes round trips
• caching individual mappings
• returns coverage regions (hinting)
• civic (all of CUS, A1NY) or geo (polygon)
• Facilitates reuse of Transport Layer Security
  (TLS)
• Returns emergency service numbers for a region
• Query for supported Service URN types

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Protocol request (mapping)
ltfindService xmlns"urnietfparamsxmlnslost1
" recursive"true" include"serviceBoundary
invalid valid unchecked"gt ltlocation
profile"urnietfparamslostlocation-profilebas
ic-civic"gt ltcivicAddress
xmlns"urnietfparamsxmlnspidfgeopriv10civic
Addr"gt ltcountrygtGermanylt/countrygt
ltA1gtBavarialt/A1gt ltA3gtMunichlt/A3gt
ltA6gtNeu Perlachlt/A6gt ltHNOgt96lt/HNOgt
ltPCgt81675lt/PCgt lt/civicAddressgt lt/locationgt
ltservicegturnservicesos.policelt/servicegt lt/findS
ervicegt
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LoST Find Service response/warning example
ltfindServiceResponse xmlns"urnietfparamsxmlns
lost1"gt ltmapping ttl1990-12-31T235960Zgt
ltdisplayName xmllang"de"gtMünchen
Polizei-Abteilunglt/displayNamegt
ltservicegturnservicesos.policelt/servicegt
ltserviceBoundary profilecivicgt
ltcivicAddress xmlns"urnietfparamsxmlnspidfg
eopriv10civicAddr"gt ltcountrygtGermanylt/co
untrygt ltA1gtBavarialt/A1gt
ltA3gtMunichlt/A3gt ltPCgt81675lt/PCgt
lt/civicAddressgt lt/serviceBoundarygt
lturigtsipmunich-police_at_example.comlt/urigt
lturigtxmppmunich-police_at_example.comlt/urigt
ltserviceNumbergt110lt/serviceNumbergt lt/mappinggt
ltvalidationgtltunchecked/gtlt/validationgt
ltwarningsgt ltlocationProfileUnrecognized
profilemartian-civic/gt lt/warningsgt
ltviagtlostesgw.uber-110.de.examplelt/viagt
ltviagtlostpolizei.munchen.de.examplelt/viagt lt/findS
erviceResponsegt
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Validation

• Determine if civic location is (partially) valid
• Returns XML tag names of components
• validated and used for mapping
• no attempt to validate (and not used)
• e.g., house number
• known to be invalid
• Return (default) PSAP based on validated elements
• May return list of guesses for correct addresses,
  if requested

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Geo support

• Which geo types should be supported?
• Point (3D) ?
• Polygon? ? may yield ambiguous answers
• more complicated shapes?
• Current proposal
• always include 2D-point
• may include other shapes

25
LoST architecture
VSP1
cluster serving VSP1
replicate root information
cluster serves VSP2
123 Broad Ave Leonia Bergen County NJ US
root nodes
NY US
NJ US
sippsap_at_leonianj.gov
search referral
Bergen County NJ US
Leonia NJ US
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LoST architecture
G
tree guide
G
G
G
broadcast (gossip)
T1 .us T2 .de
G
resolver
T2 (.de)
seeker 313 Westview Leonia, NJ US
T3 (.dk)
T1 (.us)
Leonia, NJ ? sippsap_at_leonianj.gov
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Conclusion

• Opportunity to fundamentally restructure
  emergency communications
• higher reliability with large-scale disasters
• lower cost
• richer interaction
• IETF ECRIT and SIP working group converging on
  core protocols
• service URNs
• SIP location conveyance
• LoST