911 services: wireline, wireless and VoIP Prof. Henning Schulzrinne Dept. of Computer Science Columbia University, New York hgs@cs.columbia.edu VoIP Roundtable, Washington, DC June 24, 2004

Overview E911 for wireline E911 for wireless (Phase II) Differences between phone system and VoIP Requirements and opportunities Internet standardization efforts Funding and regulation challenges

Components of emergency calling Three core components that need to be replicated – everything else are implementation details identifying emergency calls (“911”) determining the right emergency call center (PSAP) for current caller location coarse-grained location currently, two main databases: ALI for number-to-location mapping and MSAG for address verification deliver caller location to PSAP fine-grained location

E911 for wireline MSAG ALI verify address validity PSAP #1 CAMA or PRI delivers ANI (555-1234) CO Switch CAMA or SS7 Tandem Switch (911 Selective Router) 555-1234 313 Main St LEC network 555-1234  PSAP #1 ANI: 555-1234  313 Main MSAG ALI private data link 100-500 Main Street  ESN 1789 555-1234  PSAP #1, 313 Main St provisioned updates verify address validity

Wireless 911 Phase I (April 1998) Phase II (October 2001) Route all call to the appropriate PSAP based on call sector Provide cell/sector location data to PSAP Provide call back number to PSAP Phase II (October 2001) Phase I + latitude and longitude 67% 95% handset 50m 150m network 100m 300m

Wireless 911: Phase 2 pANI (ESRD or ESRK) E2 ALI ESRK or ESRD  MSC pANI (ESRD or ESRK) ISUP y N e t r s i r l i t LEC selective router Wireless Tower PDE MPC/SCP E2 ALI A-GPS, UTDOA, … S dynamic updates t ESRK or ESRD  coordinates callback number w . a p . c o ESRK = unique for call ESRD = unique for location

Problems with existing 911 system 1970s technology: CAMA trunks induce long call setup delays limited in ability to transfer information (8-10 digits) sometimes, 2,400 baud modems for database access increases call setup delays gets complicated if multiple providers ILEC vs. CLEC multiple wireless providers in one state tied to ILEC rate centers and other PSTN routing artifacts hard to move PSAPs on short notice (e.g., emergency evacuation) can’t just plug into any network termination

PSTN vs. Internet Telephony Signaling & Media Signaling & Media Internet telephony: China With a few exceptions, in Internet telephony, end systems are the only entities where signaling and media flows converge. Thus, any service that requires interaction with user media is likely to be easier to implement in the end systems. More seperately Signaling Signaling Media Belgian customer, currently visiting US Australia

How does VoIP differ from landline and wireless PSTN? All devices are nomadic new location, but same identifier Telephone companies are no longer needed there are still carriers for DSL and cable “IP dial tone” but unaware of type of data carried (voice, web, IM, …) VSP may be in another state or country anybody can be their own “VSP” Corporations and universities don’t have email carriers, either voice service provider [VSP] (TCP, RTP, SIP) Yahoo ISP (IP, DHCP) MCI dark fiber provider (λ) NYSERNET

The role of phone numbers and identifiers Wireline  line, device, subscriber & location Wireless  device, but not location VoIP (phone number and URIs): mostly identifies person, not device multiple devices located in different states can share the same number however, may not have a phone number if it does, area code may be from different state than customer billing address multiple devices device can move, while number stays the same not related to ISP

Why is VoIP ≠ wireless? VoIP devices may not have phone numbers as lookup keys e.g., sip:hgs@cs.columbia.edu Location information for devices is civil, not longitude/latitude e.g., service address for VSPs GPS not available (nor functional) on indoor devices plus, accuracy of 50 m (67%) or 150 m spans many buildings… no floor information Cell phones don’t work in our building… so A-GPS is unlikely to work there, either Plus, wireless E911 complexity due to old signaling mechanism expensive and complicated to connect to multiple wireless operators proposals to use IP-based solutions 50m

Objectives for IP-based 911 International devices must work anywhere independent of local emergency number international roaming Multimedia integrate alternate modalities such as text (TDD) and video (sign language) COTS (commercial off-the-shelf) re-use standard protocols (SIP, DNS, DHCP, HTTP, XML, …) avoid repeat of CAMA trunks Resilient easily re-route calls to any number of backup PSAPs Testable users can test operation without tying up operator resources Secure integrity, privacy and confidentiality, protection against denial-of-service attacks Technology-independent do not depend on (e.g.,) specific wireless or link technology Pro-competitive does not require carriers or gatekeepers

Opportunities for I911 More robust Additional services multiple networks and interfaces increase disaster resiliency operations can be moved easily to any network-connected location Additional services multimedia text chat replacing TTY video and images for situational awareness and instructions to civilians at scene of accident additional data hazmat data accident data (impact velocity, airbags, fuel spill, …) Better integration with first responders and public safety integration with telematics providers general awareness of call volume, origin and type information flow back to PSAP see 9/11 evacuation hand off call data, not just remote printing of address alerts and notifications to public safety and the public Cheaper to build and operate currently, small niche  expensive equipment, specialized circuits, slow upgrades should be able to leverage almost existing technology  lower risk

Three stages to VoIP 911: I1  I2  I3 may use administrative line to deliver call no location delivery I1 & I2: no modification to PSAP calls delivered to PSAP via existing technology delivers location information I3: deliver calls to PSAP via VoIP including circuit-switched calls I1, I2 and I3 will likely co-exist for some time design to allow local upgrades, without national or state-wide coordination

Three stages to VoIP 911 I1 I2 I3 when deployable? use 10-digit admin. number? mobility caller location conveyed to PSAP? PSAP modification ALI (DB) new services I1 now allowed stationary no none I2 December 2004 nomadic yes no (10-digit) I3 specified by late 2004 mobile IP-enabled replaced by DNS global number portability multimedia international calls

IETF and NENA I3 standardization efforts IETF = Internet Engineering Task Force = international open standardization body “911” sip:sos@ include civil and/or geo 911  sos 112  sos sip:psap@leonia.nj.gov provide location (civil or geo) DHCP cn=us, a1=nj, a2=bergen

Regulatory challenges Uniform technology but avoid things that don’t work internationally Distributed responsibility: VSP does not know location Residential user may have any number of VSPs like prepaid calling cards and may use any one of them for calling 911 ISP does not know VSP and whether call is voice or not  ISP needs to provide location information to end user  regulatory mandate!

Funding challenges Existing line/number model does not work longer term, no more “lines” and numbers every person may have multiple identifiers Short-term vs. long-term options Even small VSPs have a national footprint number assigned may not match location of customer VoIP has built-in global number portability can’t require to keep track of 6,000 different county 911 fees and recipients Funding collector should have direct customer relationship know accurately where customer lives have regional footprint have modest collection and distribution costs Some options: facilities-based (broadband) ISP local & state taxes non-telecom utilities (water, gas, electric) that reflect residency collect directly from household like home owners insurance

Conclusion Existing 911 system closely tied to phone system history number as universal identifier close affiliation with telephone switches incremental, constrained evolution VoIP offers opportunity to increase robustness, offer new services and decrease costs Initial international and US standardization efforts in progress IETF and NENA collaboration combines 911 and Internet expertise Initial prototypes and demonstration systems in development

Additional I1 and I2 information

Example I1 solution #1 CLEC # 1 Customer POP CLEC # 2 Example: VoxPath SS 7 Example: VoxPath End Office Switch LAN IP Phone Customer Signaling Gateway PSAP Softswitch End Office Selective Switch Router 1 2 3 4 5 6 7 8 9 * # Broadband Media Network Gateway Call Taker POP CLEC # 2 Mark Lewis

Level 3 911 Softswitch Network I1 Solution #2 Level3 Customer Softswitch Dedicated 911 trunks PSTN E911 Tandem Public Internet or Private IP Network End Users E911 Tandem IP Phones ALI DB PBX (emergency lines) ACD Level 3 911 Softswitch Network PSAP Mark Lewis

Possible I2 architecture IP PSTN Selective Router INVITE sos MG ISUP CAMA ESRK, DN  loc ALI PAM ALI-FE SIP PUBLISH E2+ ESP Local ALI National Voice N/Ws Emergency Services N/W based on slide by Martin Dawson