This feature receives a CAP trigger, stores reorigination information, and is able to forward the call such that it is routed into the IMS. It enables processing circuit-switched originating calls in the SCC-AS. Reorigination for terminating calls can be bypassed if the subscriber is not registered in the IMS network .

It is one of two features that enable circuit switched originating calls to be processed in the SCC-AS. The related feature is SCCCamelToIMSReOriginationSIP. These features are part of service centralization in the IMS.

Note Refer to Reorigination basic flow diagram to understand the role of SCCCamelToIMSReOriginationIN in reorigination.

Relevant specifications

  • 3GPP TS 23.292 and 24.292

  • GSMA IR.64.

Feature cheat sheet

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

This feature is IN only, it does not exist in a SIP B2BUA

Yes

Mobile Originating and Mobile Terminating only

 
Session_PreInitialCreditCheck

Yes. See Correlation RA

No

Stateless

1 POJO for IN behaviour

Network operator data

Common network configuration data is stored in a profile table named SCCCommonReOriginationConfigProfileTable.

For more information, see the shared configuration between the SCCCamelToIMSReOriginationSIP feature and the SCCCamelToIMSReOriginationIN feature.

Camel specific network configuration is stored in a profile table name SCCCamelToIMSReOriginationConfigProfileTable. This data is scoped by Sentinel selection key.

Attribute name Type Comments 
RoutingToInternalNetworkNumber

An enum. See RoutingToInternalNetworkNumber

Used by the IN feature when forwarding the call. For allowed values, see RoutingToInternalNetworkNumber

 
Nature

An enum. See Nature

Used by the IN feature when forwarding the call. For allowed values see Nature.

 
NumberingPlan

An enum. See NumberingPlan

Used by the IN feature when forwarding the call. For allowed values see NumberingPlan

 
BypassTermReorIfNotRegistered

Boolean

Used by the IN feature. If true, reorigination is skipped if the subscriber is not registered in the IMS network.

 
AlwaysReoriginateIfRoaming

Boolean

Used by the IN feature. If true, calls by roaming subscribers will always be reoriginated (regardless of IMS registration). If false, reoriginated or bypass behaviour will be determined by BypassTermReorIfNotRegistered.

RoutingToInternalNetworkNumber

This value is part of the CAP and ETSI INAP CalledPartyNumber.

The allowed values are:

  • ALLOWED

  • NOT_ALLOWED

The values are as if the type were specified in ASN.1 as follows:

RoutingToInternalNetworkNumber ::= ENUMERATED {
     ALLOWED     (0),
     NOT_ALLOWED (1)
 }

For more information, please see CGIN.

Nature

This value is part of the CAP and ETSI INAP CalledPartyNumber. The allowed values are:

  • SUBSCRIBER

  • UNKNOWN

  • NATIONAL

  • INTERNATIONAL

  • NETWORK_SPECIFIC

  • NETWORK_ROUTING_NATIONAL

  • NETWORK_ROUTING_NETWORK_SPECIFIC

  • NETWORK_ROUTING_WITH_CALLED_DIRECTORY

The values are as if the type were specified in ASN.1 as follows:

Nature ::= ENUMERATED {
     ... ,
     SUBSCRIBER                            (1),
     UNKNOWN                               (2),
     NATIONAL                              (3),
     INTERNATIONAL                         (4),
     NETWORK_SPECIFIC                      (5),
     NETWORK_ROUTING_NATIONAL              (6),
     NETWORK_ROUTING_NETWORK_SPECIFIC      (7),
     NETWORK_ROUTING_WITH_CALLED_DIRECTORY (8),
     ...
 }

For more information, please see CGIN.

NumberingPlan

This value is part of the CAP and ETSI INAP CalledPartyNumber.

The allowed values are:

  • SPARE_0

  • ISDN

  • SPARE_2

  • DATA

  • TELEX

  • NATIONAL_5

  • NATIONAL_6

  • SPARE_7

The values are as if the type were specified in ASN.1 as follows:

NumberingPlan ::= ENUMERATED {
     SPARE_0      (0),
     ISDN         (1),
     SPARE_2      (2),
     DATA         (3),
     TELEX        (4),
     NATIONAL_5   (5),
     NATIONAL_6   (6),
     SPARE_7      (7)
 }

For more information, please see CGIN.

Use of Correlation resource adaptor

For information about use of the Correlation RA, please see the shared Correlation RA.

Use of Cassandra-CQL resource adaptor

For information about use of the Cassandra-CQL RA, please see storing Call Information in Cassandra.

Session input and output variables

Session input variables

Attribute Name Type 
InitialDPArg

an implementation of com.opencloud.slee.resources.cgin.callcontrol.CCInitialDPArg

Session output variables

Attribute Name Type 
CCConnectArg

an implementation of com.opencloud.slee.resources.cgin.callcontrol.CCConnectArg

Statistics

SCCCamelToIMSReOriginationIN statistics are tracked by the sentinel.volte.ss7 SBB and can be found under the following parameter set:
SLEE-Usage → sentinel.volte.ss7 service → sentinel.volte.ss7 SBB → feature → SCCCamelToIMSReOriginationIN

Parameter Type Description 
Started

Counter

Incremented when the feature starts.

 
FailedToStart

Counter

Incremented when the feature failed to start due to an error.

 
IssuedWarning

Counter

Incremented when the feature raised a warning.

 
FailedDuringExecution

Counter

Incremented when the feature failed due to a major error.

 
TimedOut

Counter

Incremented when the feature timed out during execution.

 
CallReOriginated

Counter

Incremented when the call is successfully reoriginated.

 
CallReleased

Counter

Incremented when reorigination fails and the call is released.

 
ReoriginationFailedCallContinued

Counter

Incremented when reorigination fails but the call is able to be continued.

 
Misconfigured

Counter

Incremented when the feature has not been correctly configured.

 
IdpVlrNumberPresent

Counter

Incremented when the VLR number is found in the incoming InitialDP.

 
IdpVlrNumberNotPresent

Counter

Incremented when the VLR number is not found in the incoming InitialDP.

 
VisitedNetworkIdNotFound

Counter

Incremented when the feature is unable to determine the Visited Network ID.

 
VisitedNetworkIdFound

Counter

Incremented when the feature is able to determine the Visited Network ID based on the VLR address.

 
PoolAllocationFailed

Counter

Incremented when the feature fails to acquire a correlation ID from the correlation RA.

 
PoolAllocationSucceeded

Counter

Incremented when the feature acquires a correlation ID from the correlation RA.

 
OriginatingIMRNAttempt

Counter

Incremented when the feature executes reorigination for an originating call leg.

 
TerminatingIMRNAttempt

Counter

Incremented when the feature executes reorigination for a terminating call leg.

 
ReoriginationBypassed

Counter

Incremented when the feature bypasses reorigination for an unregistered subscriber.

 
StoringCorrelationDataInCassandra

Counter

Incremented when the feature stores call information data in cassandra

 
FailedToStoreCorrelationDataInCassandra

Counter

Incremented when there is a failure to store call information data in cassandra

 
PoolAllocationReleased

Counter

Incremented when an allocated correlation ID is released due to any failure

Behaviour

The SCCCamelToIMSReOriginationIN feature is triggered with an InitialDP. If the call type is not Mobile Originating or Mobile Terminating, the feature finishes execution without modifying any state.

The feature checks if the InitialDP is a CAMEL InitialDP. If not, it finishes executing without modifying any state.

The SCCCamelToIMSReOriginationIN feature checks network configuration, and if not present it informs Sentinel that it failed to execute, with an invalid configuration cause. SCCCamelToIMSReOriginationIN then finishes execution.

Once configuration is loaded, The SCCCamelToIMSReOriginationIN feature attempts to reoriginate the call (forward the call into the IMS).

If BypassTermReorIfNotRegistered = True, the feature performs a subscriber lookup in Cassandra using the IMSIDLookupFromCassandraIN feature. If the subscriber is not registered, or the registration has expired, then the value of AlwaysReoriginateIfRoaming is checked:

  • If AlwaysReoriginateIfRoaming = True and the subscriber is roaming, then reorigination is attempted.

  • If AlwaysReoriginateIfRoaming = False, or if the subscriber is not roaming, then the call is allowed to continue. A Continue is sent to the MSC, the TCAP dialog is closed, and the feature exits.

If BypassTermReorIfNotRegistered = False, or the subscriber lookup in Cassandra returns a current registration record, then reorigination is attempted.

If both BypassTermReorIfNotRegistered and AlwaysReoriginateIfRoaming are true, then reorigination will be bypassed only if the subscriber is not registered in the IMS, and they are not roaming.

Reoriginating the call

The InitialDP is checked for the presence of the CalledPartyBCDNumber parameter. If CalledPartyBCDNumber is not present, then the call fails to reoriginate.

The SCCCamelToIMSReOriginationIN feature uses the Visited Network ID Address List to check that there is a known Visited Network ID for the VLR address present in the InitialDP location information. If there is a matching ID, the feature will continue processing as normal. If there is no matching ID the call fails to reoriginate.

Note The purpose of checking for a known Visited Network ID is to avoid wasting resources establishing the SIP side of the call, only to have it fail when the SIP reorigination feature is unable to find a matching Visited Network ID.

The SCCCamelToIMSReOriginationIN feature allocates a correlation ID with the Correlation resource adaptor entity. The correlation ID is used to form the address to route the call onwards. The Correlation resource adaptor entity stores both the allocated correlation ID, and the key fields of the InitialDP argument (call information).

The call information is also stored in Cassandra, keyed on the correlation ID. If the insert into cassandra fails, then the call fails to reoriginate.

Note The call information is used in the SCCCamelToIMSReOriginationSIP feature.

The SCCCamelToIMSReOriginationIN feature then builds a destination routing address, using the correlation ID, and the network configuration for the address’s Nature, RoutingToInternalNetworkNumber, and NumberingPlan fields. The network configuration for a prefix is used if the network configuration indicates a prefix is required. This address is called the “IP Multimedia Routing Number”, or IMRN for short.

The SCCCamelToIMSReOriginationIN feature then sends a Connect operation (using the IMRN in the Destination Routing Address) and closes the TCAP dialog.

If Then

there are any problems with any of:

  • allocation of a correlation ID

  • storing call information in Cassandra

  • building the Connect operation

the call fails to reoriginate.

Failure to Reoriginate

By default, if there is any failure trying to reoriginate the call, then the SCCCamelToIMSReOriginationIN feature sends a ReleaseCall to the MSC and closes the TCAP dialog.

For terminating calls, if BypassTermReorIfNotRegistered is enabled, then the SCCCamelToIMSReOriginationIN feature instead sends a Continue to the MSC and closes the TCAP dialog.

This is because BypassTermReorIfNotRegistered being enabled indicates that the CS network is able to handle the call, so the feature allows the call continue in CS where it has a chance to succeed, rather than releasing it immediately.

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