Network operator configuration

Network configuration data is stored in a JSLEE configuration profile table named SCCCommonReOriginationConfigProfileTable.

Attribute name Type Comments 
UsePrefix

boolean

If set to true, prepends NetworkPrefix to the correlation IDs returned by the Correlation RA.

 
NetworkPrefix

String

See UsePrefix.

 
SkipHSSLookup

boolean

This decides whether the SIP feature will do a query to the HSS for the S-CSCF address or not

 
DirectRoutingURI

String

The value to use for the address to add to the route header that will be added to the INVITE after it has been reoriginated.

 
GeneratedPVNITemplate

String

A template string for the P-Visited-Network-Information header generated in the reorigination, where {mnc} and {mcc} are replaced with the MNC and MCC respectively. IR 65 versions 12 or earlier define this to be epc.ims.mnc{mnc}.mcc{mcc}.3gppnetwork.org, while later versions define this as ims.mnc{mnc}.mcc{mcc}.3gppnetwork.org.

 
PoliceOriginatingRequests

boolean

Police incoming originating requests, and reject attempts to hijack the call. Enabled by default.

 
ImsUserStateSourceForMtBypass

String

The source used to determine the IMS user state of the subscriber, during MT bypass. One of: HSS or THIRD_PARTY_REGISTRATION.

(CAMEL Only) Visited Network ID Address List

Both the IN and SIP Reorigination features, in a GSM deployment, make use of an address list for mapping a given VLR address to a Visited Network ID. This is used as a fallback if the InitialDP does not contain suitable location information.

The SIP feature uses this address list in order to populate headers on the outgoing INVITE message. The IN feature uses the address list purely as an early failure measure. It checks that there exists a matching Visited Network ID for the VLR address; this prevents network resources from being wasted establishing a SIP dialog that will ultimately fail at the SIP Reorigination feature anyway.

Note Currently, we require that the VLR address’s nature is International and its numbering plan is ISDN.

There are two profile tables associated with this address list:

  • <PlatformOperatorName>_SCCReorigination_AddressListConfigurationTable

  • <PlatformOperatorName>_SCCReorigination_AddressListEntryTable

The configuration table is a standard address list configuration table, see Address List Configuration Profile for more information. The list entry table is an extended version of the standard address list entry table (details here: Address List Entry Profile) with one additional field, a String called VisitedNetworkId. Profiles in this table must use a standard format for their names, made up of three fields: the Sentinel Selection Key, a fixed String VisitedNetworks, and the VLR address prefix to be matched when searching for a Visited Network ID. The name should be formatted like this:

  • <SelectionKey>:VisitedNetworks:<AddressPrefix>

Here’s an example:

  • OpenCloud:OpenCloud::::VisitedNetworks:6421

See the respective behaviour sections of the IN and SIP Reorigination feature pages for details on how each feature uses the address list.

For an overview of how address lists work in general, see: Address Lists.

Note We recommend that the visited network is formatted according to GSMA IR.65 section 6.2.1. I.e. is of the format epc.ims.mnc<MNC>.mcc<MCC>.3gppnetwork.org or ims.mnc<MNC>.mcc<MCC>.3gppnetwork.org, depending on the version used

Use of the Correlation RA

The IN feature/CDMA reorigination service and their SIP counterparts share (and communicate) correlation information through the Correlation RA. The resource adaptor entity used has the resource-adaptor-entity-link name sentinel-correlation-reorigination.

Note See Correlation Resource Adaptor for more information about the correlation RA.

The reorigination addresses allocated by the Correlation RA must route through to the IMS, and allow the I-CSCF to trigger the SCC-AS. Typically this is done by configuring a range of numbers that correspond to one or more IMS public service identifiers.

The sentinel-correlation-reorigination RA entity has one or more correlation ID pools.

  1. a default ID pool (optional)

  2. a set of named ID pools.

Choosing the Correlation ID Pool

Each named ID pool is identified by the NodeID and a set of prefixes for choosing/selecting the ID pool. From the Correlation RA standpoint, the prefixes can be any address string. The client to the RA provides an address that the RA uses:

In GSM Volte, the IN reorigination feature uses the MobileCountryCode extracted from LocationInformation in the triggering InitialDP

In CDMA Volte, the CDMA reorigination service uses the LocationAreaID extracted from the OriginationRequest or AnalyzedInformation

The Correlation RA performs a longestPrefix match address list search on pools with a matching NodeID for the current node. If no pool is matched by the search or no address is provided by the client to the RA, then the default pool is selected. If multiple pools match the longestPrefix address list search, the first pool in the result set is selected.

Storing Call Information in Cassandra

Call information data is stored in cassandra for two reasons:

  1. A reorigination session can be processed successfully if the SCC-AS node that received and processed the InitialDP, OriginationRequest or AnalyzedInformation trigger fails before the re-originated SIP INVITE is received by the SCC-AS.

  2. A reorigination session can be processed successfully during an SCC-AS upgrade, even if the SCC-AS node that processed the InitialDP, OriginationRequest or AnalyzedInformation trigger, and the SCC-AS node that received the re-originated SIP INVITE are members of different SCC-AS clusters.

Note The SCC Re-Origination features use the cassandra-general resource adaptor entity.

GSM Re-Origination

Call information data is stored in Cassadandra with keyspace opencloud_scc_camel_to_ims_reorigination, and table scc_camel_to_ims_reorigination_data.

A sample command for creating the opencloud_scc_camel_to_ims_reorigination keyspace in a production environment is:

CREATE KEYSPACE IF NOT EXISTS opencloud_scc_camel_to_ims_reorigination WITH REPLICATION={'class' : 'SimpleStrategy', 'replication_factor' : 3};

Replication may not be necessary for testing purposes. A sample CQL command for creating such a keyspace is:

CREATE KEYSPACE IF NOT EXISTS opencloud_scc_camel_to_ims_reorigination WITH REPLICATION={'class' : 'SimpleStrategy', 'replication_factor' : 1};

The following CQL statements creates the scc_camel_to_ims_reorigination_data table:

USE opencloud_scc_camel_to_ims_reorigination;

CREATE TABLE IF NOT EXISTS scc_camel_to_ims_reorigination_data (
  correlation_id text,
  correlation_id_expire_time timestamp,
  node_uri text,
  correlation_data blob,
  PRIMARY KEY (correlation_id)
)
WITH gc_grace_seconds = 600; // 10 minutes
Field Type Comments 
 correlation_id

text

The correlation ID related to the InitialDP, and the re-triggered SIP INVITE.

 
 correlation_id_expire_time

timestamp

Represents the maximum time, after which the correlation ID allocation is considered to have expired

 
 node_uri

text

The URI of the SCC-AS node that assigned the correlation ID

 
 correlation_data

blob

Call information that is stored on the InitialDP, and used when processing the re-triggered SIP INVITE

The correlation_id is the primary key.

CDMA Re-Origination

Call information data is stored in Cassadandra with keyspace opencloud_scc_cdma_to_ims_reorigination, and table scc_cdma_to_ims_reorigination_data.

Field Type Comments 
 correlation_id

text

The correlation ID related to the OriginationRequest or AnalyzedInformation, and the re-triggered SIP INVITE.

 
 correlation_id_expire_time

timestamp

Represents the maximum time, after which the correlation ID allocation is considered to have expired

 
 node_uri

text

The URI of the SCC-AS node that assigned the correlation ID

 
 correlation_data

blob

Call information that is stored on the OriginationRequest or AnalyzedInformation, and used when processing the re-triggered SIP INVITE

The correlation_id is the primary key.

Reorigination basic flow

The following diagrams cover some basic reorigination scenarios for GSM and CDMA networks.

GSM Reorigination Scenario 1

In the following diagram:

  • Sentinel VoLTE acts as the SCC-AS (node 101 and node 102).

  • The “IN feature” is the SCCCamelToIMSReOriginationIN feature.

  • The “SIP feature” is the SCCCamelToIMSReOriginationSIP feature.

  • Correlation data is stored in an external cassandra DB. The Sentinel SCC-AS reads call information data from cassandra when the re-originated SIP INVITE is received on a different SCC-AS node that received the InitialDP.

  • The User-Data-Request and Answer will not occur if the SkipHSSLookup flag is set to true and instead the value in the DirectRoutingURI will be used.

This flow diagram shows a configuration where the SkipHSSLookup flag is set to false, so that the SCC-AS looks up the HSS and acts as a B2BUA between the I-CSCF and the S-CSCF after B number restoration. The InitialDP is received on SCC-AS (node 101), and the SIP INVITE is received in a different SCC-AS (node 102).

reorig roaming detection use hss lookup

GSM Reorigination Scenario 2

As a variation to the above diagram, the following shows the effect of configuring:

  1. SkipHSSLookup flag set to true

  2. DirectRoutingURI set to the I-CSCF

reorig roaming detection skip hss lookup

CDMA Reorigination Scenario

In the following diagram:

  • Sentinel VoLTE acts as the SCC-AS.

  • The “CDMA Service” is the CDMA ReOrigination service.

  • The “SIP feature” is the SCCCDMAReOrigination feature.

  • Correlation data is stored in an external cassandra DB. The Sentinel SCC-AS reads call information data from cassandra when the re-originated SIP INVITE is received on a different SCC-AS node that received the OriginationRequest or AnalyzedInformation.

  • The User-Data-Request and Answer will not occur if the SkipHSSLookup flag is set to true and instead the value in the DirectRoutingURI will be used.

This flow diagram shows a configuration where:

  1. SkipHSSLookup flag set to true

  2. DirectRoutingURI set to the I-CSCF

cdma reorig roaming detection skip hss lookup

For further information related to headers set in the outgoing SIP INVITE, please refer to SIP headers in the outgoing INVITE.

Reorigination MT Bypass flow

The following diagrams show an MT scenario where the served user is not registered in the IMS and the SCCCamelToIMSReOriginationIN feature bypasses terminating reorigination.

The difference between each scenario is the method used to determine if the served user is registered in the IMS.

GSM MT Bypass, Query HSS for IMS User State

In the following diagram:

The InitialDP is received on SCC-AS (node 101). The IMSUserStateLookupFromHSS feature queries the HSS for the IMS user state of the served user (as identified by the IMS public identity derived from the InitialDP). In this scenario the served user is not registered in the IMS, so the SCCCamelToIMSReOriginationIN sends a Continue and closes the dialog with the MSC.

reorig query hss ims user state

GSM MT Bypass, Derive IMS User State by Querying Third Party Registration Data in Cassandra

In the following diagram:

The InitialDP is received on SCC-AS (node 101). The IMSIDLookupFromCassandraIN feature checks the Associated URIs table in the Cassandra database for entries related to the served user (as identified by the IMS public identity derived from the InitialDP). In this scenario there are no entries in the Associated URIs table (therefore the served user is not registered in the IMS). The SCCCamelToIMSReOriginationIN sends a Continue and closes the dialog with the MSC.

reorig query cassandra ims user state

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Sentinel VoLTE Version 4.1