The incoming SIP INVITE message contains the
“emergency” value in the Priority header.
Notes:
This parameter is applicable to FXS/FXO.
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 initiated by the FXO (i.e., Tel-to-
IP calls), new incoming emergency IP-to-Tel calls are
dropped.
MLPP and Emergency services can also be configured in a
Tel Profile.
For more information, see 'Pre-empting Existing Call for E911
IP-to-Tel Call' on page 256.
Emergency E911 Parameters
Web/EMS: Emergency Numbers
[EmergencyNumbers]
Defines a list of “emergency” numbers.
For FXS: When one of these numbers is dialed, the outgoing
INVITE message includes the SIP Priority and Resource-Priority
headers. If the user places the phone on-hook, the call is not
disconnected. Instead, a Hold Re-INVITE request is sent to the
remote party. Only if the remote party disconnects the call (i.e., a
BYE is received) or a timer expires (set by the
EmergencyRegretTimeout parameter) is the call terminated.
For FXO: These emergency numbers are used for the
preemption of E911 IP-to-Tel calls when there are unavailable or
busy channels. In this scenario, the device terminates one of the
busy channels and sends the emergency call to this channel.
This feature is enabled by setting the CallPriorityMode
parameter to 2 (“Emergency”). For a description of this feature,
see 'Pre-empting Existing Call for E911 IP-to-Tel Call' on page
256.
The list can include up to four different numbers, where each
number can be up to four digits long.
Example: EmergencyNumbers = ‘100’,’911’,’112’
Web: Emergency Calls Regret
Timeout
EMS: Emergency Regret Timeout
[EmergencyRegretTimeout]
Defines the time (in minutes) that the device waits before
tearing-down an emergency call (defined by the parameter
EmergencyNumbers). Until this time expires, an emergency call
can only be disconnected by the remote party, typically, by a
Public Safety Answering Point (PSAP).
The valid range is 1 to 30. The default is 10.
Note: This parameter is applicable only to FXS interfaces.
Multilevel Precedence and Preemption (MLPP) Parameters