Specifications

Emergency 911 Operations
B – 2 ShoreTel, Inc.
How 911 Calls Work
The figure below shows a simple 911 call-flow scenario.
Figure B-1 Simplified 911 call flow scenario
1
A 911 call is placed from an office and is routed through the ShoreTel equipment
to an outbound trunk. Caller ID information is provided by the PBX (for PRI
trunks) or by the service provider (for non-PRI trunks).
2 The Public Switched Telephone Network (PSTN) forwards the call to the service
provider’s Central Office (CO).
3 The CO then passes the call to a Public Safety Answering Point (PSAP). This is
the location of the emergency services dispatcher.
4 The dispatcher at the PSAP gets a “screen pop” which displays information
contained in a 911 database. The database contains a mapping between the
caller ID number and the geographic location of the caller.
5 The dispatcher sends emergency response personnel to the calling party’s
location.
COPSTN
Small office PSAP / dispatcher
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