Emergency E911 Phone Number Services; Pre-Empting Existing Calls For E911 Ip-To-Tel Calls; Enhanced 9-1-1 Support For Lync Server 2010 - AudioCodes Mediant 2000 User Manual

26.5

Emergency E911 Phone Number Services

This section describes the device's support for emergency phone number services.

26.5.1 Pre-empting Existing Calls for E911 IP-to-Tel Calls

If the device receives an E911 call from the IP network destined to the Tel, and there are
unavailable channels (e.g., all busy), the device terminates one of the calls (arbitrary) and
then sends the E911 call to that channel. The preemption is done only on a channel
pertaining to the same Trunk Group for which the E911 call was initially destined and if the
channel select mode (configured by the ChannelSelectMode parameter) is set to a value
other than "By Dest Number" (0).
The preemption is done only if the incoming IP-to-Tel call is identified as an emergency
call. The device identifies emergency calls by one of the following:

The destination number of the IP call matches one of the numbers defined by the
EmergencyNumbers parameter. For E911, you must defined this parameter with the
value "911".

The Priority header of the incoming SIP INVITE message contains the "emergency"
value.
Emergency pre-emption of calls can be enabled for all calls, using the global parameter
CallPriorityMode, or for specific calls using the Tel Profile parameter CallPriorityMode.
Notes:
•
For Trunk Groups configured with call preemption, all must be configured to MLPP
[1] or all configured to Emergency [2]. In other words, you cannot set some trunks
to [1] and some to [2].
•
The global parameter must be set to the same value as that of the Tel Profile
parameter; otherwise, the Tel Profile parameter is not applied.
•
If you configure call preemption using the global parameter and a new Tel Profile
is subsequently added, the TelProfile_CallPriorityMode parameter automatically
acquires the same setting as well.
•
This feature is applicable to CAS and ISDN interfaces.

26.5.2 Enhanced 9-1-1 Support for Lync Server 2010

The Enhanced 9-1-1 (E9-1-1) service is becoming the mandatory emergency service
required in many countries around the world. The E9-1-1 service, based on its predecessor
911, enables emergency operators to pinpoint the location (granular location) of callers
who dial the 9-1-1 emergency telephone number.
Today, most enterprises implement an IP-based infrastructure providing a VoIP network
with fixed and nomadic users, allowing connectivity anywhere with any device. This,
together with an often deployed multi-line telephone system (MLTS) poses a challenge for
E9-1-1 due to the difficulty in accurately locating the E9-1-1 caller.
This section describes the E9-1-1 solution provided by Microsoft Lync Server 2010
(hereafter referred to as Lync Server 2010), and the deployed AudioCodes ELIN Gateway
which provides the ISDN (or CAMA) connectivity to the PSTN-based E9-1-1 emergency
providers. This section also describes the configuration of AudioCodes ELIN Gateway for
interoperating between the Lync Server 2010 environment and the E9-1-1 emergency
provider.
User's Manual 338
Mediant 2000
Document #: LTRT-68822