A primer on E 9-1-1
E911... you've heard the term but
what exactly does it mean and what does it have to do with location-based industries? In order to familiarize
you with enhanced 9-1-1 (e911), we've provided a short primer and listed examples and pointers to agencies that are addressing e911 concerns
By GeoCommunity Staff
WHAT IS ENHANCED 911?
When a caller dials 911, the address and phone number of the caller is
displayed on a screen at the 911 center. Enhanced 911 or E911 provides dispatchers with the location of callers and
their phone number. This is also known as ANI/ALI - automatic number information and automatic location information.
Sounds simple but when you factor in wireless and cellular
calls the issue of location gets a bit tricky. Currently, many 911 centers don't receive important
location data from wireless telephone calls. This results in confusion and problems for
emergency dispatch services. Also, areas that have multiple 911 centers may have problems routing calls as a result of insufficient
Wireless E9-1-1 is one of the most pressing challenges facing the
nation's public safety community. Roughly 25% to 30% of all
E9-1-1 calls are currently placed from wireless phones, and this
percentage is expected to increase sharply as wireless phone
usage continues to accelerate over the next few years.
So, What's Being done?
The FCC has ordered cellular carriers to address the issue in an effort to help 911 centers.
Phase I of the FCC plan requires carriers to transmit a number for each call. If additional information is required, the dispatcher
can call the number and obtain 'rough' locational information about the caller.
The second phase requires more precise location data to be transfered with the call, allowing dispatchers
to trace the callers location to within 410 feet. Under the current plan, cellular companies have until October 1, 2001 to
add this capability.
Phase 1 Requirements (by 4/1/98)
Wireless service providers were required by the
FCC to have the capability to send wireless 911
calls to an E911 PSAP containing two important
sets of data (presuming the 911 jurisdiction has
implemented a cost recovery mechanism for the
carrier and has requested the service):
The location of the cell tower through which
the E911 call was processed.
The mobile dialing number (MDN) or "call
back number" of the wireless phone placing
the 911 call.
Phase 2 Requirements (by 10/1/2001)
Wireless service providers are required by the FCC
to have the ability to send the actual caller's
location (to within 410 ft. of accuracy, 67% of the
time) to the E911 PSAP (presuming the 911
jurisdiction has implemented a cost recovery
mechanism for the carrier and has requested the