AudioCodes Mediant 500 E-SBC User Manual page 425

User's Manual
Notes:
•
MLPP is supported on ISDN PRI interfaces.
•
The device provides MLPP interworking between SIP and ISDN (both directions).
•
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.
The Resource Priority value in the Resource-Priority SIP header can be any one of those
listed in the table below. A default MLPP call Precedence Level (configured by the
SIPDefaultCallPriority parameter) is used if the incoming SIP INVITE or PRI Setup
message contains an invalid priority or Precedence Level value respectively. For each
MLPP call priority level, the Multiple Differentiated Services Code Points (DSCP) can be
set to a value from 0 to 63.
Table 26-4: MLPP Call Priority Levels (Precedence) and DSCP Configuration Parameters
MLPP Precedence Level
0 (lowest)
2
4
6
8
9 (highest)
The device automatically interworks the network identity digits (NI) in the ISDN Q.931
Precedence Information Element (IE) to the network domain subfield of the INVITE's
Resource-Priority header, and vice versa. The SIP Resource-Priority header contains two
fields, namespace and priority. The namespace is subdivided into two subfields, network-
domain and precedence-domain. Below is an example of a Resource-Priority header
whose network-domain subfield is "uc", r-priority field is "priority" (2), and precedence-
domain subfield is "000000":
Resource-Priority: uc-000000.2
The MLPP Q.931 Setup message contains the Precedence IE. The NI digits are presented
by four nibbles found in octets 5 and 6. The device checks the NI digits according to the
translation table of the Department of Defense (DoD) Unified Capabilities (UC)
Requirements (UCR 2008, Changes 3) document, as shown below:
Level IE
0000
0001
Version 6.8
Precedence Level in Resource-
Priority SIP Header
routine
priority
immediate
flash
flash-override
flash-override-override
Table 26-5: NI Digits in ISDN Precedence
Network Domain in SIP Resource-Priority Header
425
26. Configuring Supplementary Services
DSCP Configuration Parameter
MLPPRoutineRTPDSCP
MLPPPriorityRTPDSCP
MLPPImmediateRTPDSCP
MLPPFlashRTPDSCP
MLPPFlashOverRTPDSCP
MLPPFlashOverOverRTPDSCP
uc
cuc
Mediant 500 E-SBC