Emergency Services Access (Esa); Routing Esa Calls - Avaya 1000 Installation And Commissioning Manual

Emergency Services Access (ESA)

Routing ESA calls

Important:
Do not route ESA calls to a node that has no direct ESA trunks.
Ideally, route ESA calls directly over Central Office (CO) trunks to the Public Safety Answering Point
(PSAP). In those cases where this routing is not possible, do not route ESA calls to nodes that have
no direct ESA trunks.
The implications of routing calls to nodes without direct ESA trunks are as follows:
• At the node without the direct ESA trunks, the node cannot route the ESA call directly to the
PSAP. Instead, that node must re-route the call to another node. This re-routing is an
unnecessary use of resources.
• If the node is a Avaya Communication Server 1000E node, the only tandem trunks are IP Peer
trunks. There is no way to specify the appropriate rerouting digits (that is, Prepend Digits) to
reroute the ESA call to another node with direct ESA trunks.
Therefore, if you are unable to route ESA calls directly to the PSAP, the next best practice is to
route ESA calls to nodes with direct ESA trunks.
Emergency call routing
A Call Server can provide service to IP phones across multiple emergency jurisdictions. This can
also occur with traditional non-IP equipment in the form of remote peripheral equipment (for
example, Carrier Remote, Fiber Remote).
An emergency call should be handled by the designated means for the phone location (for example,
local security desk or local PSAP). The emergency call should be routed to a service at the current
location of the phone.
PSTN routing: Enhanced 911 versus Basic 911
Currently, no industry-standard (wireline) solution exists for routing an emergency call to an arbitrary
PSAP, and delivering location data. With Enhanced 911 (E911), multiple Emergency Service Zones
(PSAP areas) are connected by an E911 Tandem system. The PSTN first routes an emergency call
to the E911 Tandem, which contains a Selective Router. The Selective Router looks up the caller's
ANI in its Selective Routing Data Base (which is synchronized with the ALI database) to determine
the correct PSAP and then routes the emergency call appropriately. Hence, the call can be routed to
any CO in the correct E911 Tandem area. The Selective Router automatically routes the call to the
appropriate PSAP based on the ANI.
In areas that support Basic 911, the route to the PSAP is determined by the PSTN access point.
Hence, the call must be routed to the nearest CO to the caller. ESA can specify a route for each
ERL, which meets the more stringent requirement of Basic 911. In areas with Enhanced 911,
system administrators have more flexibility in how to route their emergency calls to the PSTN.
June 2014 Branch Office Installation and Commissioning
Comments? infodev@avaya.com
Emergency Services Access (ESA)
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