Emergency Calling in SIP Henning Schulzrinne with Anshuman

Emergency Calling in SIP Henning Schulzrinne (with Anshuman Rawat, Matthew Mintz-Habib and Xiaotao Wu) Dept. of Computer Science Columbia University hgs@cs. columbia. edu SIP 2005 - 1/27/05 Emergency calling 1

Overview n n n Vo. IP emergency communications What makes emergency calling hard? Stages of deployment n n n I 1: quick fixes I 2: backward-compatible I 3: end-to-end IP Initial prototype NENA + IETF efforts SIP 2005 - 1/27/05 Emergency calling 2

Vo. IP emergency communications emergency call emergency alert (“inverse 911”) dispatch civic coordination SIP 2005 - 1/27/05 Emergency calling 3

Current wireline calls dial 911, 112 route call to right PSAP E 911 TANDEM OFFICESRDB SUBSCRIBER 1 3 2 5 4 END OFFICE map ANI to civic location PSAP ANI COMMON EQUIPMENT ATTENDENT POSITIONS 7 ALI HOST 5 7 6 (Brian Rosen) SIP 2005 - 1/27/05 Emergency calling 4

Wireless (Phase II) Calls Ai Di MSC Cellsite E 12 (ISUP) E 3 (ANSI-41) ESNE (Selective Router) CRDB (ANSI-41) CAMA PSAP E 11 (LSP) PDE E 5 MPC MSC MPC E 2 (ESP) Mobile Switching Center Mobile Position Center ESME (ALI Database) CRDB Coordinate Routing Database PDE Position Determining Entity (Brian Rosen) SIP 2005 - 1/27/05 Emergency calling 5

Components of emergency calling Contact well-known number or identifier Route call to locationappropriate PSAP Deliver precise location to call taker to dispatch emergency help SIP 2005 - 1/27/05 now transition all IP 112 911 dial 112, 911 signal sos@ selective router VPC DNS phone number location (ALI lookup) in-band key location in-band Emergency calling 6

What makes Vo. IP 112/911 hard? POTS PSTN-emulation Vo. IP end-to-end Vo. IP (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-topeer device voice provider = line provider (~ business relationship) 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 SIP 2005 - 1/27/05 Emergency calling 7

More than pain… n Multimedia from the caller n n Data delivery n n n e. g. , CPR training Load balancing and redundancy n n n caller data: floor plan, hazmat data, medical alerts measurement data input: automobile crash data, EKGs, … Delivering video to the caller n n video capture from cell phones video for sign language text messaging and real-time text for the deaf currently only limited secondary PSAP Vo. IP can transfer overload calls anywhere Location delivery n n carry location with forwarded and transferred calls multiple location objects (civic + geo) SIP 2005 - 1/27/05 Emergency calling 8

Core long-term requirements n Media-neutral n n Work in systems without a voice service provider n n many enterprises will provide their own local voice services Allow down-stream call data access n n voice (+TDD) first, IM and video later as well as access to other “tertiary” data about the incident Globally deployable n n n independent of national emergency number (9 -1 -1, 1 -1 -2, etc. ) respect jurisdictional boundaries – minimize need for crossjurisdictional coordination allow usage even if equipment and service providers are not local n n Testable: n n n travel, imported equipment, far-flung locations verifiable civic addresses (“MSAG validation”) call route validation Secure and reliable SIP 2005 - 1/27/05 Emergency calling 9

Staged deployment n ~6, 134 PSAPs in North America n n n 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 1970 s telecom technology n n n “CAMA” (operator) trunks limited to delivering 8 (regional) or 10 digits (national) of information already facing pressure from supporting cellular services n n n Phase I (cell tower and face) and Phase II (caller geo location) EU: smaller number of PSAPs, but often without location delivery Initial version (“I 1”): n n n dial 10 -digit administrative number like telematics services does not deliver caller location to PSAP SIP 2005 - 1/27/05 Emergency calling 10

Three stages to Vo. IP 911 spec. available? use 10 digit admin. number? mobility callback number to PSAP? caller location to PSAP? PSAP modificatio n ALI (DB) modification new services I 1 now allowed stationary no no none I 2 June 2005 no stationary nomadic yes no (8 or 10 digit) update none I 3 2005 no stationary nomadic mobile yes IP-enabled ALI not needed MSAG replaced by DNS location inband GNP multimedia international calls SIP 2005 - 1/27/05 Emergency calling 11

I 1. 5: Level 3 ESGW solution • uses Level 3 as CLEC to feed ALI information to local ILEC • requires emergency services GW for each tandem • only works for non-ported numbers • does not work for mobile users SIP 2005 - 1/27/05 Emergency calling 12

I 1. 5: Global Crossing Vo. IP 911 transport SIP 2005 - 1/27/05 Emergency calling 13

I 2 architecture (draft) IP domain Emergency Services Provider Network Routing Proxy & Redirect server(s) Call server/ proxy server PSTN v 6 ESGW(s) v 4 v 5 v 4 v 1 IP Domain E 9 -1 -1 Selective Router v 2 User Agent VPC VPC v 0 DHCP v-e 2 ESZ RDB LIS v 7 SIP 2005 - 1/27/05 routing database SRDB MSAG VDB DBMS DNS PSAP ALIDB DB v 8 v 3 location information service E 9 -1 -1 Selective Router Vo. IP positioning center validation database Emergency calling 14

I 2 interfaces Interface Participants Protocol(s) Description v 0 LIS to UA DHCP conveys location to endpoint v 1 UA to CS SIP (+ others) recognize emergency call transport location object v 2 Proxy to VPC XML query/response location ESRN, ESQK v 3 VPC to LIS ? VPC gets location from location key in signaling message v 4 CS/routing proxy to ESGW SIP ESRN and ESGW inserted v 5 CS to redirect server SIP Redirect server returns call routing information (ESRN, ESQK) in 3 xx v 6 CS to routing proxy SIP transport location object v 7 location validation DNS, ? LIS requests validation of address v 8 VPC to ERDB ? VPC sends LO, gets ESQK ve-2 VPC to ALI-DB SIP 2005 - 1/27/05 E 2+ (wireless) Emergency calling 15

I 3: Location-based call routing – UA knows its location GPS INVITE sips: sos@ 48° 49' N 2° 29' E outbound proxy server DHCP 48° 49' N 2° 29' E Paris fire department SIP 2005 - 1/27/05 Emergency calling 16

I 3 (long-term) architecture components Common URL for emergency calls 1. n sips: sos@home-domain Convey local emergency number to devices Allow devices to obtain their location 2. 3. n n directly via GPS indirectly via DHCP (MAC switch port location database) on LAN via LLDP (802. 1 ab, TIA LLDP-MED) initially, often through manual configuration Route calls to right destination 4. n using look-up in device or proxy SIP 2005 - 1/27/05 Emergency calling 17

Location, location n Location locate right PSAP & speed dispatch In the PSTN, local 9 -1 -1 calls remain geographically local In Vo. IP, no such locality for VSPs n n n most VSPs have close to national coverage Thus, unlike landline and wireless, need location information from the very beginning Unlike PSTN, voice service provider doesn’t have wire database information n VSP needs assistance from access provider (DSL, cable, Wi. Max, 802. 11, …) SIP 2005 - 1/27/05 Emergency calling 18

Columbia/Map. Info prototype n Goal: build prototype Vo. IP SIP-based emergency calling system n n n including caller end system call routing (DNS) PSAP infrastructure Use commodity components where possible Test reliability and redundancy SIP 2005 - 1/27/05 Emergency calling 19

Components sipd SIP proxy server database-backed DNS server SIP phone web server SQL database for call routing sipc SIP user agent geo-coding, PSAP boundaries GIS software for call location plotting No endorsement implied – other components likely will work as well SIP 2005 - 1/27/05 Emergency calling 20

Call routing SIP 2005 - 1/27/05 Emergency calling 21

Detail: I 3 - DNS-based resolution DHCP INFORM psap. state. vt. gov SIP w/location MAC loc Perl sip-cgi script psap. state. vt. gov DNS NAPTR: addison. vt. us algonquin-dr. addison. vt. us … proprietary TCP-based protocol 151. algonquin-dr. addison. vt. us. sos-arpa. net SIP 2005 - 1/27/05 Emergency calling 22

3 rd party call control SIP 2005 - 1/27/05 Emergency calling 23

3 rd Party Call Control Flow SIP 2005 - 1/27/05 Emergency calling 24

Call taker setup SIPc client receives calls SIP 2005 - 1/27/05 Geo. Lynx software displays caller location Emergency calling 25

Geo. Lynx displays location Geo. Lynx listens for commands from SIPc Emergency calling SIP 2005 - 1/27/05 26

Emergency call conferencing PSAP brings all related parties into a conference call Hospital Fire department INVITE Conference server Recorder REFER 3 rd party call control media INVITE info INVITE REFER INVITE media info PSAP Caller SIP 2005 - 1/27/05 Emergency calling 27

Scaling n n NENA: “estimated 200 million calls to 91 -1 in the U. S. each year” approximately 6. 3 calls/second n n n if 3 minute call, about 1, 200 concurrent calls typical SIP proxy server (e. g. , sipd) on 1 GHz PC can handle about 400 call arrivals/second thus, unlikely to be server-bound SIP 2005 - 1/27/05 Emergency calling 28

Current standardization efforts n NENA (National Emergency Number Association) n n n ETSI OCG – EMTEL n n exploratory – also emergency notification NRIC n n I 2 and I 3 architecture requirements based on operational needs of PSAPs goals and long-term architecture IETF: n n individual and SIPPING drafts for identifier, call routing, architecture SIP and DNS usage possibly new protocols for lookups ECRIT BOF (pre-WG) at IETF-61 in Washington, DC SIP 2005 - 1/27/05 Emergency calling 29

Current IETF documents n draft-taylor-sippingemerg-scen-01 (expired) n n draft-schulzrinne-sipping -emergency-req-01 n n scenarios, e. g. , hybrid Vo. IP-PSTN abstract requirements and definitions n draft-ietf-sipping-sos-00 n n draft-rosen-dns-sos-01 n n n overall architecture for emergency calling n SIP 2005 - 1/27/05 Emergency calling new DNS resource records for location mapping RFC 3825 draft-schulzrinne-sipping -emergency-arch-02 n describes ‘sos’ SIP URI “Dynamic Host Configuration Protocol Option for Coordinatebased Location Configuration Information” draft-ietf-geopriv-dhcpcivil-04 n DHCP option for civic 30 addresses

Conclusion n n Emergency calling services necessary condition for first-line wireline-replacement services US: large numbers of PSAPs financially exhausted from Phase II wireless support n n often 1970 s technology – end of bailing wire reached Long-term opportunity for better services SIP 2005 - 1/27/05 Emergency calling 31