Pre-Empting Existing Calls For E911 Ip-To-Tel Calls - AudioCodes Mediant 1000B User Manual

a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=sendrecv

Example B: The detection of a Wink signal generates the following SIP INFO
message:
INFO sip:4505656002@192.168.13.40:5060 SIP/2.0
Via:
From: port1vega1 <sip:06@192.168.13.2:5060>
To: <sip:4505656002@192.168.13.40:5060>;tag=132878796-
1040067870294
Call-ID: 0010-0016-D69A7DA8-1@192.168.13.2
CSeq:2 INFO
Content-Type: application/broadsoft
Content-Length: 17
event flashhook

26.11.3 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 Phone 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 FXO, CAS and ISDN interfaces.
•
For FXO interfaces, the preemption is done only on existing IP-to-Tel calls. In
other words, if all the current FXO channels are busy with calls that were
answered by the FXO device (i.e., Tel-to-IP calls), new incoming emergency IP-to-
Tel calls are rejected.
User's Manual
SIP/2.0/UDP 192.168.13.2:5060
Mediant 1000B Gateway & SBC
434 Document #: LTRT-27034