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 value is 10. 
Note: This parameter is applicable only to FXS interfaces. 
Multilevel Precedence and Preemption (MLPP) Parameters 
Web: MLPP DiffServ 
EMS: Diff Serv 
[MLPPDiffserv] 
Defines the DiffServ value (differentiated services code 
point/DSCP) used in IP packets containing SIP messages that 
are related to MLPP calls. This parameter defines DiffServ for 
incoming MLPP calls with the Resource-Priority header. 
The valid range is 0 to 63. The default value is 50. 
Notes: 
  The same value must be configured for this parameter and 
the parameter PremiumServiceClassControlDiffServ. 
  Outgoing calls are tagged according to the parameter 
PremiumServiceClassControlDiffServ. 
Web/EMS: Precedence Ringing 
Type 
[PrecedenceRingingType] 
Defines the index of the Precedence Ringing tone in the Call 
Progress Tones (CPT) file. This tone is used when the 
parameter CallPriorityMode is set to 1 and a Precedence call is 
received from the IP side. 
The valid range is -1 to 16. The default value is -1 (i.e., plays 
standard ringing tone). 
EMS: E911 MLPP Behavior 
[E911MLPPBehavior] 
Defines the E911 (or Emergency Telecommunication 
Services/ETS) MLPP Preemption mode: 
  [0] = (Default) Standard Mode - ETS calls have the highest 
priority and preempt any MLPP call. 
  [1] = Treat as routine mode - ETS calls are handled as 
routine calls. 
[RPRequired] 
Determines whether the SIP resource-priority tag is added in the 
SIP Require header of the INVITE message for Tel-to-IP calls.  
  [0] Disable = Excludes the SIP resource-priority tag from the 
SIP Require header. 
  [1] Enable = (Default) Adds the SIP resource-priority tag in 
the SIP Require header. 
Note: This parameter is applicable only to MLPP priority call