This feature determines the transferable set for access transfer .

The transferable set is a phrase from 3GPP 24.237, and includes sessions that will be transferred during an access transfer, and those that are considered superfluous.

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

Both Originating and Terminating

SCCAccessTransfer_SipAccess_SessionStart

None

None

Stateless

POJO

Prerequisite features

Session input and output variables

Session input variables

Variable Type Description
AccessTransferType

AccessTransferType (Enum)

This feature will only run when this field is set to eSRVCC_Not_Anchored, eSRVCC_Anchored, or SRVCC

ASURI

String

The SIP URI of the current node

Session output variables

Variable Type Description
MostRecentlyActive

TrackedSession (POJO)

Contains all the information in TrackedDialogKeys about the most recently active session

SuperfluousSessions

Set<TrackedSession>

A set of all of the other sessions found from querying the TrackedDialogKeys table

AccessTransferIsLocal

boolean

True if the MostRecentlyActive’s ASURI field is the same as the current nodes ASURI

Statistics

SCCDetermineTransferableSet statistics are tracked by the sentinel.volte.sip SBB and can be found under the following parameter set in REM:
SLEE-Usage → sentinel.volte.sip service → sentinel.volte.sip SBB → feature → SCCDetermineTransferableSet
or with rhino-stats:
"SLEE-Usage.Services.ServiceID[name=sentinel.volte.sip,vendor=OpenCloud,version=2.8.0].SbbID[name=sentinel.volte.sip,vendor=OpenCloud,version=2.8.0].feature.SCCDetermineTransferableSet"

Name Description
Started

Incremented each time the feature runs

FailedToStart

Incremented when a fatal error occurs before feature execution

IssuedWarning

Incremented when a non-fatal error occurs during feature execution

FailedDuringExecution

Incremented when a fatal error occurs during feature execution

TimedOut

Incremented when feature execution does not complete within a reasonable time frame

SessionOwnershipQuery

Incremented when the feature sends a query to the session ownership facility

SessionOwnershipError

Incremented when a TrackedDialogKeys lookup fails with a Session Ownership error

SessionOwnershipSuccess

Incremented when a TrackedDialogKeys lookup returns successfully

SessionOwnershipNoDataFound

Incremented when no matching tracked dialog keys entries were found in the session ownership facility

FoundTrackedSession

Incremented when the feature successfully finds a Session Ownership Record resulting from a TrackedSession

SavedSessionToTransfer

Incremented when the feature saves the most recently active TrackedSession to session state

SavedSuperfluousSessions

Incremented when the feature saves all of the remaining TrackedSession’s to session state

SessionOwnershipAsyncQueryTimeSuccess

Samples the elapsed time between starting a query and a success response arriving from the session ownership facility

SessionOwnershipAsyncQueryTimeFailure

Samples the elapsed time between starting a query and a failure response arriving from the session ownership facility

Behaviour

This feature uses the P-Asserted-Identity header from the handover INVITE as an "additional key" to look up a Session Ownership Record. Prior sessions for the purposes of SCC write Session Ownership Records saved by the AccessLegTracking and External Session Tracking features.

Each returned Session Ownership Record is converted into an API object named TrackedSession.

The TrackedSession with the most recent LastActiveTime is stored in Session State as the MostRecentlyActiveSession. All other Tracked Sessions are stored in the SuperfluousSessions set. The feature sets the AccessTransferIsLocal flag in Session State if the MostRecentlyActiveSession has an OwnerURI value the same as the current node’s ASURI.

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Sentinel VoLTE Version 2.8.0