2 Understanding ZBA Functionality and ZBA Logic

Zero Balance Application (ZBA) is a business logic application that functions within the DCA framework.

The DCA frame must first be active before activating the ZBA to access the ZBA GUI menu functionality.

Note:

The DCA framework is a set of APIs and services made available to DCA developers (internal or external) who need to development application that run in the Diameter application layer of DSR.

When a mobile data service subscriber initiates a data session, a network Element (PCEF or CTF) might attempt to set up a data session for the subscriber and query the OCS for service units. In case the subscriber has no credit in their account, the OCS rejects the request, usually with an indication that the subscriber has no credit. However, in most cases the PCEF, or other Charging Trigger Functions (CTFs), continues to attempt to query the OCS. This can create an overload on the OCS to handle requests for subscribers that are always denied during the period in which the subscriber has no credit.

The purpose of the ZBA is to detect when a subscriber, identified by a MSISDN, has a zero balance in the account, the ZBA under certain configurable conditions, might respond on behalf of the OCS and reduce the number of queries the OCS must handle for subscribers who temporarily have no credit.

ZBA is configured as the owner of a UDR database. To avoid overloading of ZBA, the Application Routing Table (ART) is configured to route only CCR- I/E type messages to ZBA.

ZBA can be enabled and disabled as a DCA framework. Disabling ZBA on a specific site is possible only if ZBA has been disabled on all the DA-MPs on that specific site.

If ZBA is in the DCA framework GUI menu, this indicates that the application is already enabled. However, it does not guarantee that it is provisioned. After ZBA is installed, a manual enablement is necessary on at least one DA-MP server.

Note:

You can enable or disable ZBA from Diameter, and then Maintenance, and then Applications screens on the SOAM GUI. When the application is initially installed, it is disabled and it must be manually enabled.

The ZBA functionality varies between the SOAM and NOAM. The following menu options are available on the NOAM:

• The Custom MEALs menu provisions the measurements linked to the ZBA application.
• The General Options sets the options of the application.
• The Trial MP Assignment chooses the MP to run the application.
• The Application Control menu creates a new development environment and modifies them.

The SOAM has the same menu options in read only and an additional menu option called System Options where the behavior of the application can be configured in case of errors.