Emergency Calling Summary and Open Issues Henning Schulzrinne

Emergency Calling – Summary and Open Issues Henning Schulzrinne Columbia University

Emergency Calling Components n Sub-problems: n n Universal identifier Call routing User location Differs depending on whether local gateway, remote gateway or IP-enabled PSAP

Universal identifier n n n Proposal: sip: sos@local-domain + local tel numbers (911, 112, …) Thus, resolution in outbound proxy Difficulty: obtaining local domain n n Works if client uses home domain, but longer resolution path and international issues Special identifier, e. g. , sip: sos@localhost?

Call routing n Need to find appropriate emergency call center n Local gateway n n Remote gateway n n Just use appropriate emergency number need to dial 10 -digit number IP ECC n need to find appropriate ECC

Call routing proposal EPAD REGISTER sip: sos 302 Moved Contact: sip: sos@psap. leonia. nj. us Contact: tel: +1 -201 -911 -1234 Location: 07605 INVITE sip: sos Location: 07605 SIP proxy INVITE sip: sos@psap. leonia. nj. us Location: 07605

Call routing n n Requires no changes to proxy or SIP Allows multiple EPAPs to REGISTER for redundancy

Call routing – open issues n EPAD realistic? n n EPAD needs to be told about proxy n n n database of 10 -digit ECC numbers needed for telematics rare – “fill out web form” provide secret – ensures that only SIP proxy owner can (usefully) do this How to authenticate EPAD? n n Shared secret – works for standard proxy Certificate with credential (requires proxy knowledge)

Call routing - alternatives n Configure proxy manually to route emergency calls to designated address n n anycast? Service discovery n SLP

User location n n Rely on geopriv output – architecture not clear (special protocol with GML? ) Insert into SIP request by n n UA (manual configuration, GPS, …) Outbound proxy (MAC backtracking, database, …)