Mlpp Preemption Events In Sip Reason Header - AudioCodes Mediant 800B User Manual

By default, the device maps the received Resource-Priority field of the SIP Resource-
Priority header to the outgoing ISDN PRI Precedence Level (priority level) field as follows:

If the network-domain field in the Resource-Priority header is "uc", then the device
sets the Precedence Level field in the ISDN PRI Precedence Level IE according to
Table 5.3.2.12-4 (Mapping of RPH r-priority Field to PRI Precedence Level Value):
Table 26-5: Mapping of SIP Resource-Priority Header to PRI Precedence Level for MLPP
MLPP Precedence Level
Routine
Priority
Immediate
Flash
Flash Override

If the network-domain field in the Resource-Priority header is any value other than
"uc", then the device sets the Precedence Level field to "0 1 0 0" (i.e., "routine").
This can be modified using the EnableIp2TelInterworkingtable field of the ini file parameter,
ResourcePriorityNetworkDomains.
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 1050.

26.12.1 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"

Reason: preemption ;cause=3 ;text="Generic Preemption"

Reason: preemption ;cause=4 ;text="Non-IP Preemption"
This Reason cause code indicates that the session preemption has occurred in a non-
IP portion of the infrastructure. The device sends this code in the following scenarios:
•
The device performs a network preemption of a busy call (when a high priority
call is received), the device sends a SIP BYE or CANCEL request with this
Reason cause code.
•
The device performs a preemption of a B-channel for a Tel-to-IP outbound call
request from the softswitch for which it has not received an answer response
(e.g., Connect), and the following sequence of events occurs:
a.
User's Manual
PRI Precedence Level
4
3
2
1
0
The device sends a Q.931 DISCONNECT over the ISDN MLPP PRI to the
partner switch to preempt the remote end instrument.
Mediant 800B Gateway and E- SBC
SIP Resource-Priority Header Field
556
0
2
4
6
8
Document #: LTRT-10296