Providing Emergency Services in Internet Telephony

1
Providing Emergency Services in Internet Telephony

• Henning Schulzrinne and Knarig ArabshianDepartmen
  t of Computer ScienceColumbia University
• hgs,knarig_at_cs.columbia.edu

2
Overview

• IP telephony (SIP)
• E-911 service
• Emergency calling using SIP
• Emergency notification systems
• SIP based notification
• Conclusions

3
IP telephony (SIP)

• Address based on email (alice_at_home.com)

• Outgoing proxy
• DNS SRV for SIP home.com?pc1.home.com
• pc1.home.com ?129.59.19.140
• INVITE alice_at_home.com
• INVITE alice_at_m2.home.com (proxy mode)

office.com
(1)
Bob
Alice
(3)
(4)
m2.home.com
Columbia.edu
home.com
Cisco.com
pc1.home.com
4
E-911 ServiceFour components needed
2) Call routing to an emergency response
center-PSAP
1) Universal number such as 911
3) Caller Identification Who is calling?
caller-id to avoid prank call 4) Caller
Location Where is he calling from? Address for
speedy response
1-212-9397063 613 CEPSR, Columbia Univ
5
E-911 ServiceHow it works?
Selective routing database

• Emergency Service Primary PSAP
• Number 2129119345
• ? Secondary PSAP
• 2129119456

Prefix Emergency Service
Number 212939xxxx ? 2345
SRDB
2129119345
Central office
2129397063 ? 613 CEPSR, 120th st Broadway and
Amsterdam Ave
Telco DB
1-212-9397063
6
Emergency Call using SIP(Legacy PSAP sees the
gateway)
ESRDB
SRDB
SIP-PSTN gateway (switch room)
PSAP
PSTN
939713x
Central office
2129397130 ? 606 CEPSR
IP network
Sends fire-fighters to the switch room.
Telco DB
128.59.19.61
(multimedia lab)
7
Emergency Call using SIP(IP-enabled PSAP is
aware of IP telephony)
PSAP
Outbound Proxy
IP Network
LAN
Richer Communication Envorinment video to
instruct caller in first aid or use sign
language, text-based messaging, etc.
128.59.19.61
(multimedia lab)
8
Architecture for Internet Telephony
Use local switch tables to get the address of the
caller
PSAP
EPAD
INVITE sipsos_at_example.com SIP/2.0Location Rm.
523, 123 Main Street Centerville, NY
302 Moved Temporarily Contact tel[phone]
INVITE sip1-212-911-1234_at_gw-r-us.comLocation
Rm. 523, 123 Main Street Centerville, NY
Outbound Proxy
9
What are Emergency Notification Systems?

• Allow government officials to notify a community
  of an emergency and precautionary measures that
  must be taken
• Different emergency situations and alert methods
• Fire Alarms, Earthquake or chemical spills
  indicated by sirens, Notifying public of
  terrorist attacks via radio/TV broadcasting
• Emergency Alert System (EAS)
• Controlled by the government and used for wide
  area emergency notification

10
SIP-based Emergency Notification

• Use SUBSCRIBE/NOTIFY methods
• Clients will subscribe to servers for emergency
  notification
• Servers will notify clients of particular
  emergency situation

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CLIENT (SUBSCRIBER)
SERVER (NOTIFIER)
SUBSCRIBE sipalerts_at_leonia.nj.us SIP/2.0Event
alert.mathazFrom sipalice_at_example.comTo
sipalerts_at_leonia.nj.us
SIP/2.0 202 Accepted From sipalice_at_example.com
Expires 86400
NOTIFY sipalerts_at_leonia.nj.us SIP/2.0Event
alert.mathazTo sipalice_at_example.comFrom
sipalerts_at_leonia.nj.usltsoapbodygt
ltmemergencygt lttypegtfirelt/typegt
ltmaterialgtwoodlt/materialgt
ltalarmsgt2lt/alarmsgt lt/memergencygtlt/soapgt
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Alerting Hierarchy
United States Federal Govt.
NJ State Govt.
Alabama
Alaska
New Jersey
Wisconsin
Wyoming
NOTIFY
SUBSCRIBE
Atlantic
Bergen
13
Benefits

• Device Neutrality
• More Information and Automated Action
• Lower resource consumption
• Integration with current systems
• Out-of-area notification

14
Conclusion and Future Work

• IP telephony gives opportunity to enhance
  existing emergency services by creating more
  functional, robust and flexible systems
• Future/Ongoing work includes
• Location resolution of caller and finding nearest
  PSAP
• Building a demo of an emergency notification
  system using SOAP