This feature enables Access Leg Tracking for the current session if the UE is SR-VCC capable and has a C-MSISDN .

Feature cheat sheet

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

SCC

Yes

Both Originating and Terminating

SipAccess_SessionStart

Yes

None

Stateless

POJO

Consults third party registration state

Pre-requisite features

Session input and output variables

Session input variables

Session state variable name Type Comments 
RegistrationRecord

Object

This contains all of the registration information for the served user.

 
CMSISDN

String

A string set to a non-null value if there is a C-MSISDN provisioned for the user, and if the user is logged in;
if the user is not logged in, or if the MSRN is set, then it is set to null.

 
AccessLegTrackingKeys

Set<String>

The tracking keys to use for the current sessions.

 
SentinelSelectionKey

SentinelSelectionKey

Used to check for session plans that do not require session tracking.

Session output variables

Session state variable name Type Comments 
AccessLegTrackingKeys

Set<String>

The tracking keys to use for the current session. The feature adds to this set.

 
AccessLegTrackingActive

boolean

Set to true if the UE has a C-MSISDN and UE-SRVCC capability.

 
AccessLegUESRVCCSupport

Enumeration

Set to one of NONE, DEFAULT, ALERTING, PRE-ALERTING.

Statistics

SCCDetermineExternalSessionTracking 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 → SCCDetermineExternalSessionTracking
or with rhino-stats:
"SLEE-Usage.Services.ServiceID[name=sentinel.volte.sip,vendor=OpenCloud,version=3.1.0].SbbID[name=sentinel.volte.sip,vendor=OpenCloud,version=3.1.0].feature.SCCDetermineExternalSessionTracking"

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

 
FoundTrackingKey

Incremented when the Served User has an IMS registration with UE-SRVCC-Capability and a C-MSISDN

 
ExternalSessionTrackingDisabled

Incremented when the Served User does not have an IMS registration with UE-SRVCC-Capability and a C-MSISDN

 
PartialDialogExternalSessionTrackingEnabled

Incremented when the Served User supports UE-SRVCC-Capability and has the g.3gpp.ps2cs-srvcc-orig-pre-alerting media feature tag

Behaviour

The feature scans all Third Party Registration information for the Served User’s IMS Public Identity. If any registration indicates that the device has support for UE-SRVCC-Capability, and it has an assigned C-MSISDN, then:

  1. Session Tracking is enabled via setting the AccessLegTrackingActive flag in session state to TRUE,

  2. the value of the C-MSISDN is added to the AccessLegTrackingKeys set in session state, and

  3. the AccessLegUESRVCCSupport session state field is set to DEFAULT

  4. the feature increments the FoundTrackingKey statistic and finishes execution

Otherwise the feature sets the AccessLegTrackingActive flag to FALSE, increments the ExternalSessionTrackingDisabled statistic and finishes execution.

Note When running a T-ADS only session plan, this feature immediately determines that session tracking is not required and skips the registration data check.
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Sentinel VoLTE Version 3.1.0