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Emergency services for SIP

Emergency services for SIP. Henning Schulzrinne. Emergency services. Two types of emergency services: emergency calls ("911", "112") emergency notification ("inverse 911") emergency calls are hard: PSTN gateway dialing 911 may be located anywhere, far away from IP phone

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Emergency services for SIP

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  1. Emergency services for SIP Henning Schulzrinne

  2. Emergency services • Two types of emergency services: • emergency calls ("911", "112") • emergency notification ("inverse 911") • emergency calls are hard: • PSTN gateway dialing 911 may be located anywhere, far away from IP phone • VPNs  IP address may not reveal network location

  3. Emergency services • More than just replicating PSTN: • multimedia • video monitoring of accident scene or victim • video instruction in first aid • better than TTY for hearing-impaired • transmit biometric data • Easier to create multiple backup PSAPs

  4. PSTN emergency calling • Basic 911: call number, get routed to one Public Safety Answering Point (PSAP) • since 1968 in the United States • 93% of population covered by 911 • Enhanced 911: • route based on CLID (cannot be suppressed) • provide user location • started in 1970s, now 95% • see Bellcore SR4163 for details • see 47 USC 251 for legal mandate

  5. Wireless emergency calling • FCC Phase I: caller ID, cell site • FCC Phase II mandates user location: • Handset-based: • 50 meters for 67 percent of calls • 150 meters for 95 percent of calls • Network-based: • 100 meters for 67 percent of calls • 300 meters for 95 percent of calls

  6. VoIP emergency calls • Work for both "legacy" PSAPs and IP-based PSAPs • Define "sos" universal emergency address • find location of phone based on • street address  geocoding  long/lat, or • mobile: longitude, latitude • find appropriate jurisdiction and PSAP • use national database: long/lat  PSAP • find ESR (routing number)  call appears like 911 call • convey location to PSAP

  7. Emergency identifier • Requirements: • dialable from all SIP devices • universally recognized • note: SOS  "save our souls"! • not quite unassigned – consider 112@ and 911@? • Also allow "sos.fire" and others for specialized emergency services • Use sip:sos@home-domain to make handling predictable • intermediate proxies may deflect

  8. Routing emergency calls 302 Moved Contact: sip:sos@psap.leonia.nj.us Contact: tel:+1-201-911-1234 EPAD REGISTER sip:sos Location: 07605 INVITE sip:sos Location: 07605 SIP proxy INVITE sip:sos Location: 07605 INVITE sip:sos@psap.leonia.nj.us Location: 07605

  9. Where is the phone? • Regular GPS doesn't work well • doesn't work indoors • long time to first fix: 30"-15' • assisted GPS (A-GPS) • HDTV-based • Landline and 802.11 phones: • LAN jack tracing via traceroute, ARP, Cisco Discovery Protocol (CDP) and SNMP vLAN tables • 802.11 field strength triangulation (e.g., Microsoft, VTT) • hardware identification: • IR/RF tags • user data entry

  10. "Bergen County" 400 Broad Avenue Leonia, NJ Leonia "sos" A@ B@ C@ Alice ISDN B "911" Fort Lee ISDN D SS7 ISUP Bob RTP SIP call setup UDP audio (IP or circuit) IP SIP registration Bergen County analog phone IP phone 911 deployment SIP 0 1 0 c1.leonia.us IP UDP, TCP IP c2.leonia.us c1.fortlee.us IP 0 1 0

  11. Open issues • What needs to be standardized? • Are there any other UA behaviors? • prevent accidental disconnect • bypass carrier authentication • e.g., 3G requirement of REGISTER before calls? • Myth: During PSTN 911 calls, certain features (three-way calls, hang-up) are unavailable • true only for Basic 911

  12. Emergency notification • notify public officials and citizens of emergencies: • "tornado coming" • "fugitive alert" • current systems are typically single-mode (fax, telex, phone, TV, loudspeaker) • don't scale well • very limited information content • don't reach citizens outside calling area • people at work • hard to authenticate

  13. SIP-based emergency notification • SIP has scalable event notification feature • use for hierarchical notification reflecting civil lines of authority • use XML/WSDL message bodies to semantically describe emergency: • location • type of emergency • instructions • ... • allow automated reaction: • routing to legacy systems (pagers, police radios) • translation

  14. Emergency notification

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