AudioCodes Media Pack MP-124, User Manual

Page: 257 / 584

Version 6.6 257 MP-11x & MP-124
User's Manual 24. Configuring Supplementary Services
MLPP is typically used in the military where, for example, high-ranking personnel can
preempt active calls during network stress scenarios such as a national emergency or
degraded network situations.
MLPP can be enabled for all calls, using the global parameter, CallPriorityMode, or for
specific calls using the Tel Profile parameter, CallPriorityMode.
Notes:
•
For Hunt 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.
The Resource Priority value in the Resource-Priority SIP header can be any one of those
listed in the table below. For each MLPP call priority level, the Multiple Differentiated
Services Code Points (DSCP) can be set to a value from 0 to 63.
Table 24-1: MLPP Call Priority Levels (Precedence) and DSCP Configuration Parameters
MLPP Precedence Level Precedence Level in Resource-
Priority SIP Header
DSCP Configuration Parameter
0 (lowest) routine MLPPRoutineRTPDSCP
2 priority MLPPPriorityRTPDSCP
4 immediate MLPPImmediateRTPDSCP
6 flash MLPPFlashRTPDSCP
8 flash-override MLPPFlashOverRTPDSCP
9 (highest) flash-override-override MLPPFlashOverOverRTPDSCP
Notes:
•
If required, you can exclude the "resource-priority” tag from the SIP
Require header in INVITE messages for Tel-to-IP calls when MLPP
priority call handling is used. This is configured using the RPRequired
parameter.
•
For a complete list of the MLPP parameters, see 'MLPP and Emergency
Call Parameters' on page
534 .
24.11.1 MLPP Preemption Events in SIP Reason Header
The device sends the SIP Reason header (as defined in RFC 4411) to indicate the reason
and type of a preemption event. The device sends a SIP BYE or CANCEL request, or SIP
480, 486, 488 response (as appropriate) with a Reason header whose Reason-params can
includes one of the following preemption cause classes:

Reason: preemption ;cause=1 ;text=”UA Preemption”

Reason: preemption ;cause=2 ;text=”Reserved Resources Preempted”