This feature assists with originating sessions towards the Conference Factory by augmenting the REFER request sent from the UE to the Conference Factory .

The moderator UE sends a REFER request to add and remove conference participants. Such a REFER request contains a Refer-To header that is often re-written by Application Servers. The original value as sent by the UE is necessary for Re-INVITE based conferencing. This can be achieved through two means:

  1. copying the original value into a different header - the approach taken by this feature, or

  2. disabling any Application Server invocation for originating attempts towards the Conference Factory - the approach taken prior to introduction of this feature when re-INVITE based conference is used.

Feature cheat sheet

B2BUA Instance SAS Support Originating / Terminating Point(s) in Session Plan Network Operator Data Subscriber Data Stateful or Stateless POJO or SBB Feature Other notes

SCC

Yes

Originating only

SubscriptionSipRequest

None

None

Stateless

POJO

Copies Refer-To header to X-MSW-Original-Refer-To

Prerequisite features

  • DetermineCallType

  • DetermineVoltePlanId

Network operator data

There is none.

Subscriber data

There is none.

Session input and output variables

Session input variables

N/A

Session output variables

N/A

Statistics

SCCAugmentRefer statistics are tracked by the sentinel.volte.sip SBB and can be found under the following parameter set:
SLEE-Usage → [sentinel.volte.sip service name] → [sentinel.volte.sip SBB name] → feature.SCCAugmentRefer

Statistic Increments when…​
Started

The feature is started.

FailedToStart

Sentinel VoLTE encounters an error while attempting to start the feature.

IssuedWarning

A non-fatal problem is encountered and the feature and issues a warning.

FailedDuringExecution

A fatal problem is encountered and the feature cannot execute correctly.

TimedOut

The feature takes too long to complete and Sentinel VoLTE aborts execution.

ReceivedRefer

The feature is triggered on a REFER request.

AugmentedRefer

The REFER request contains a Refer-To header

Behaviour

This feature ignores any Trigger that is not a SIP REFER request. If the REFER request has a Refer-To header the feature copies the incoming Refer-To header into an outbound X-MSW-Original-Refer-To header.

This is to facilitate conference moderator Access Transfer where an originating SCC-AS must be present between the moderator UE and the call to the Conference Factory.

The rationale for this behaviour is that the Refer-To header tends to be re-written by routing B2BUA’s and the original value must be visible to the Conference Factory for re-INVITE based flows.

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Sentinel VoLTE Version 2.9.0