Pre-Empting Existing Calls For E9-1-1 Calls; Psap Callback To Skype For Business Clients For Dropped E9-1-1 Calls - AudioCodes Mediant 1000 User Manual

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15.7.3.2 Pre-empting Existing Calls for E9-1-1 Calls

If the ELIN device receives an E9-1-1 call from the IP network and there are unavailable
channels (for example, all busy), the device immediately terminates one of the non-E9-1-1
calls (arbitrary) and accepts the E9-1-1 call on the freed channel:

SBC: The preemption is done only on a call pertaining to the same source IP Group
from which the E9-1-1 call is received, or the same destination IP Group (i.e., PSAP
Server).

Gateway: The preemption is done only on a channel pertaining to the same Trunk
Group for which the E9-1-1 call was initially destined. For example, if an E9-1-1 call is
destined for Trunk Group #2 and all the channels belonging to this group are busy, the
device terminates one of the calls in this group to free a channel for accepting the E9-
1-1 call.
This feature is initiated only if the received SIP INVITE message contains a Priority header
set to "emergency", as shown below:
PRIORITY: emergency

15.7.3.3 PSAP Callback to Skype for Business Clients for Dropped E9-1-1 Calls

As the E9-1-1 service automatically provides all the contact information of the E9-1-1 caller
to the PSAP, the PSAP operator can call back the E9-1-1 caller. This is especially useful in
cases where the caller disconnects prematurely. However, as the Enterprise sends ELINs
to the PSAP for E9-1-1 calls, a callback can only reach the original E9-1-1 caller using the
device to translate the ELIN number back into the E9-1-1 caller's extension number.
In the ELIN table of the device, the temporarily stored From header value of the SIP
INVITE message originally received from the E9-1-1 caller is used for PSAP callback.
When the PSAP makes a callback to the E9-1-1 caller, the device translates the called
User's Manual
Mediant 1000B Gateway & E-SBC
288 Document #: LTRT-27045