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Wireless E911 Guide CG-EWCG-001
Overview of E911 Issue 3, January 6, 2004
wireless carrier providing a real-time update to the ALI databases during 9-1-1 call processing. Phase
2 requires both of the data elements provided in Phase 1 plus the longitude and latitude of the caller’s
location when they dialed 9-1-1. BellSouth supports E2 connectivity between MPCs and the ALI database
hosts as defined in BellSouth Technical Reference TR73610, Issue 2. BellSouth will deliver the lat / long
data to the PSAP in the ALI response message as described in BellSouth Technical Reference TR73528,
Issue 6. Wireless Carriers must ensure dynamically updated records will comply with TR73528 when
delivered to the PSAP. These Technical References may be found on the following web site:
Note: To receive the maximum benefit of E911, the initial ALI database record must be assigned an
MSAG valid address even if the tower is located in a rural area. MSAG valid addresses are
obtained from the addressing authority in the E911 area where the cell site is located.
1.1.4 Premises Based ALI Systems
Premises based ALI systems may have a separate database, software, and hardware located on the E911
Customer premises. Wireless Carriers must identify all premises based systems in their service areas and
comply with any special data or interface requirements. Carriers should meet with PSAPs to determine
if selective routing or direct trunking is used to deliver 911 calls. If calls are not selectively routed to
premises based ALI systems, the carrier may need to deliver wireless 911 calls to the PSAP administrative
lines or use other arrangements as negotiated with the PSAP. This guide does not address issues related to
premises based ALI systems.
1.2 PSAP Display
The PSAP display for the ANI and ALI has been configured so that the PSAP attendant can immediately
recognize from the English Language Translations (ELT) that the call is being made from a wireless
device. The ALI response may contain the cell site sector location, subscriber call back number, and
lat/long when available. An example of a typical PSAP display is shown. This screen/display will vary
based on which PSAP equipment is chosen by the E911 Customer.
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