1. Thoughts on VoIP and Emergency Calling
Henning Schulzrinne
Columbia University
November 11, 2018

2. VoIP emergency communications
emergency call
emergency alert
(“inverse 911”)
dispatch
civic coordination
November 11, 2018

3. Reliability issues
Selective routers can only route to alternate (fixed) trunks
Typically, two
No MSAG or ALI information for out-of-area numbers
Numbers may not be unique (if 8 digit numbers)
No GIS information for out-of-area numbers
November 11, 2018

4. Goals
Any PSAP should be able to back up any other PSAP almost instantaneously
Preferably without prior arrangement
It should be possible to create a new PSAP in short order
E.g., a university computer lab or a (commercial) call center
Ingredients needed:
Internet bandwidth
PCs with audio capability
Call taker staff
November 11, 2018

5. How to achieve these goals?
Allow every SR and VoIP phone to reach every PSAP
E.g., via gateway into IP (Internet, ESN)
Provide mapping independent
November 11, 2018

6. The core problem Voice Service Provider (VSP) sees emergency call
but does not know caller location
ISP/IAP knows user location
but does not handle call
November 11, 2018

7. New model Clear separation of ISP and VSP roles
ISP provides location, VSP provides call routing
IP addresses are not sufficient to locate end systems
Probable regulatory requirement: ISPs must provide (civic/geo) location information to their subscribers even if they do not offer VoIP services
E.g., via DHCP or other standards-based mechanism
November 11, 2018

8. UA recognition & proxy resolution
mapping
9-1-1
provider.com
INVITE urn:service:sos
To: urn:service:sos
<location>
INVITE
To: urn:service:sos
<location>
November 11, 2018

9. UA recognition & proxy resolution (proxy location determination)
mapping
9-1-1
provider.com
INVITE urn:service:sos
To: urn:service:sos
INVITE
To: urn:service:sos
Location: <location>
November 11, 2018