Pre-Empting Existing Calls For E911 Ip-To-Tel Calls - AudioCodes Mediant 800B User Manual

From: "0123456789"
<sip:333333444444@audiocodes.com>;tag=1c771623824
To: <sip:301@10.33.37.79;user=phone>
Call-ID: 77162335841200014153@10.33.37.78
CSeq: 1 INVITE
Contact: <sip:101@10.33.37.78>
Supported: em,100rel,timer,replaces,path
Allow:
REGISTER,OPTIONS,INVITE,ACK,CANCEL,BYE,NOTIFY,PRACK,REFER,INFO
,SUBSCRIBE,UPDATE
User-Agent: Audiocodes-Sip-Gateway-FXO/v.6.00A.020.077
Privacy: none
P-Asserted-Identity: "0123456789"
<sip:3333344444@audiocodes.com>
Content-Type: application/sdp
Content-Length: 253
v=0
o=AudiocodesGW 771609035 771608915 IN IP4 10.33.37.78
s=Phone-Call
c=IN IP4 10.33.37.78
t=0 0
m=audio 4000 RTP/AVP 8 0 101
a=rtpmap:8 pcma/8000
a=rtpmap:0 pcmu/8000
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.
User's Manual
SIP/2.0/UDP 192.168.13.2:5060
Mediant 800B Gateway and E-SBC
432 Document #: LTRT-10286