Service Selection
When an IDP is sent by an MSC, it is sent to the Prepaid SCP (PPSCP) through the vSTP for GTT processing. As such, the message will contain MTP DPC = vSTP PC and SCCP CdPA = PPSCP GTA with RI = GT. Because the MTP destination of the message is the vSTP, the message is delivered to the vSTP for SCCP processing.
The SCCP CdPA Translation Type (TT), Numbering Plan (NP), Nature of Address (NAI), Global Title Indicator (GTI), and Subsystem Number (SSN) parameters are examined to determine which SCCP service is being requested.
The parameters can match a Service Selector entry that indicates the IDPR service.
This combination of parameters may or may not be enough to determine that the message should receive IDP Relay service. For example, if other IDP messages could be received that do not require IDP Relay, the Service Selectors could be identical for all IDP messages. Therefore, additional service selection criteria are required.
If the parameter combination is consistent with service selectors for the IDP Relay service, the SCCP CdPA GTA digits are compared to the provisioned Common Screening List (CSL) GT list of Prepaid SCP GTs. This list should contain all SCPs that could be the recipient of an IDP message for prepaid query.
- The TCAP Operation Code is examined; if it is not IDP, the IDP message is passed to standard GTT processing.
- The combination of INAP/CAP Service Key and EventTypeBCSM from the message is compared to provisioned DS of Service Key + Event Type entries from the CSL SKBCSM list. If the message Service Key + EventTypeBCSM matches one of the provisioned SKBCSM combinations pointing to IDP Relay service, then the message is sent for IDP Relay service.
IDP messages not matching these criteria either fall through to standard GTT processing, or are sent to another SCCP service for which the criteria match.
