Title: A VoIP Emergency Services Architecture and Prototype
1A VoIP Emergency Services Architecture and
Prototype
- Matthew Mintz-Habib, Anshuman Rawat,
- Henning Schulzrinne, and Xiaotao Wu
- Internet Real Time Laboratory
2Overview
- Motivation
- Issues
- Solution
- Assumptions
- Architecture
- Prototype
- Conclusion
3Motivation
- Growing VoIP networks
- but no standard solution to reliably provide
emergency services - FCC
- IP vital to emergency communications
- VoIP operators must be able to steer 911 calls to
the geographically appropriate emergency call
center - Opportunity
- enhance the existing emergency call handling
infrastructure
4Issues
- Identifying
- emergency number
- Routing
- which PSAP
- Presenting
- locate the caller
- Scalability
- Security
5Assumptions
- VoIP (SIP)-capable end systems
- VoIP (SIP)-capable PSAP
- Location inserted by origin
- outbound proxy
- originating device (e.g., via DHCP)
- Capable infrastructure
- proper DNS records
- DHCP
- conference server
6Architecture
NENA long-term architecture (I3) for emergency
communications
7Four phases
Identify emergency calls
Determine location
tel112 is this an emergency number?
Route to appropriate PSAP
Present to call takers
8Four phases
DHCP GPS RFID Bluetooth Manual
Identify emergency calls
Determine location
sipsos_at_example.com tel911 tel112
MapInfo GeoLynx
Route to appropriate PSAP
Present to call takers
DNS NAPTR
9Prototype
DHCP server
DNS server
Envinsa
GPS RFID Manual
INFORM
NAPTR w/ loc
location
location
PSAP
media
SOAP w/ loc
SIPConf
sipsos w/ loc or w/out loc
emergency call taker
sippsap_at_domain w/ loc or
sipsos tel911
sipd
INVITE
SIP UA
sipd
INVITE w/ loc
INVITE w/ loc
location
sipsos w/out loc
911
3pcc controller
GeoLynx
PSTN GW
POTS/ Wireless network
10Components
No endorsement implied other components likely
will work as well
11DHCP for locations
- Modified dhcpd (ISC) to generate location
information - Use MAC address backtracing to get location
information
DHCPINFORM 0011209da003
DHCP server
DHCP answer 0US1CA2LOS ANGELES 3LONG
BEACH 6HYATT AVE19300
RFC3825
draft-ietf-geopriv-dhcp-civil
12MIME with pidf-lo
- ------- _ZGY1NTFlZDJkMDkxY2FkMTIxMWI2MzIzNjE1M2U0
OTY - MIME-Version 1.0
- Content-Type application/pidfxml
- Content-Transfer-Encoding 8bit
- lt?xml version"1.0" encoding"ISO-8859-1"?gt
- ltpresence xmlns"urnietfparamsxmlnspidf
-
- entity"sipxyz_at_example.com"gt
- lttuple id"28185"gt
- ltstatusgt
- ltclcivilAddressgt
- ltclcountrygtuslt/clcountrygt
- ltclA1gtcalt/clA1gt
- lt/statusgt
- ltcontact priority"0.8"gtlt/contactgt .
- INVITE sipsos_at_example.com SIP/2.0
- To ltsipsos_at_example.comgt
- Call-ID 763782461_at_192.168.1.106
- From sipxyz_at_example.com tag820953399325.192.16
8.1.106 -
- Content-Type multipart/mixed boundary
- CSeq 1 INVITE
- Content-Length 1379
- ------ _ZGY1NTFlZDJkMDkxY2FkMTIxMWI2MzIzNjE1M2U0O
TY - MIME-Version 1.0
- content-Type application/sdp
- Content-Transfer-Encoding 8bit
- (SDP content)
draft-ietf-geopriv-pidf-lo
13Routing to correct PSAP
14Get PSAP from DNS (civic)
SIP CGI script
NAPTR SOSECC
DNS Query
15Get PSAP from DNS (geo)
- Route based on long/lat
- Drill-down search transfers geo to civic
- Final query is based on civic address
NAPTR SOSPOLYGON
DNS
-118.18944, 33.76694
SIP CGI script
AK, AL, , WV, WY
boundary (XML)
boundary (XML)
long_beach.los_angeles. ca.us.sos-arpa.net
boundary (XML)
boundary (XML)
boundary (XML)
16Bring related parties together
Bring all related parties into a conference call.
Hospital
Fire department
Conference server
PSAP UA
Recorder
Caller
3pcc controller
17Scaling
- NENA estimated 200 million calls to 9-1-1 in
the U.S. each year - ? approximately 6.3 calls/second
- if 3 minute call, about 1,200 concurrent calls
- typical SIP proxy server (e.g., sipd) on 3 GHz
CPU/1G RAM PC can handle about 800 call
arrivals/second - thus, unlikely to be server-bound
18Security
- secure DNS
- TLS
- sRTP
- https
- domain-based certificate
- firewall/NAT and NAT traversal
19Demo Ft. Wayne, IN (August 17, 2004)
20Conclusion and future work
- First prototype demoed, worked very well
- Latency and Security
- More features
- Route calls to preferred call takers
- Accept-Language, Accept, Supported
- SIP caller preferences and callee capabilities
- Multimedia (audio, video, text)
- Data delivery (floor plan, CPR how-to)
- Auto-answering similar incidents based on
time/location
21DHCP for locations (cont.)
- ip_phone 1
- host sip0011209da003
- next-server ng911serv.irt.cs.columbia.edu
- hardware ethernet 0011209da003
- fixed-address 128.59.17.59
- option tftp-server-name "128.59.19.174"
- option host-name "sip0011209da003"
- 0US1CA2LOS ANGELES3LONG BEACH6HYATT
AVE19300 - option loc-civil 555321243412b4c4f5320
414e47454c45533a4c4f4e4720424541
434869485941545420415645133333030
-
dhcpd.conf
22DNS entries