What is a promotion?

A promotion is a charging mechanism that deflects charging requests away from the OCS, to be charged to a specially provisioned account called a promotion bucket. The promotion bucket can be stored for example in session state or in a database which Sentinel can query and update directly. Each promotion consists of two main elements: a promotion bucket, which may be shared by multiple promotions, and a promotion condition.

sentinel promotions
Important Sentinel’s promotions are not a rating engine as found in an OCS — they can be used to charge eligible services against a particular bucket of units, but they cannot determine or affect the rate at which services are charged.

Promotion buckets

Promotion buckets are buckets of units provisioned on a per-subscriber or per-session basis. Each bucket has a unique name and is configured in Sentinel to be of one of the following access types:

  • External Database

  • Cassandra

  • SLEE Profile

  • Sentinel Session State

  • Unlimited.

A subscriber can be eligible for more than one promotion and thus units may be charged to different buckets for the same subscriber. A promotion bucket is distinct from the user’s main account in the OCS, in that it is held in session state or a separate database maintained by Sentinel directly. It usually (though not always) represents a particular unit-/type/ and provides units to be charged by one or more promotions.

Promotion conditions

A promotion condition is a filter that defines which charging requests are eligible for the promotion. Factors in this condition can include: service, amount of units, current time, and so on. The filter may be hardcoded in Java or scripted in the extensible Sentinel PromotionScript DSL for fast and easy deployment.

Below is an example of a scripted promotion condition for “anytime free data”:


Why promotions?

Sentinel’s promotions meet a number of needs in real-time session control:

Granting special offers

Sentinel’s promotions make it simple to grant special offers and customized charging plans to subscribers for any combination of services and conditions. This is a key competitive advantage, because it significantly reduces the time-to-market on newly developed offers. It also opens up a whole range of options for charging plans.


A key benefit of Sentinel’s promotions is to reduce OCS requests during special offers such as a “1000 free SMS” deal. This can be a major cost-saver when offering promotions to customers, as OCS’s are commonly licensed on a session or request per-second basis, and requests can increase dramatically during such special offers.

Maintaining fair-use policies

Sentinel’s promotions can also be used to maintain fair-use provisions, by restricting subscribers from abusing “unlimited” offers.

OCS failure-handling policies

In the event of OCS failure, an OCS Failure Handling Promotions can be used to provide a grace period to allows service to continue for a limited time. In an event-based charging scenario, a limited number of service events may be allowed until full service is restored. All accounting data can be reconciled later by using the call detail records that Sentinel records for each session.

Online or offline charging

If sessions are categorized at session start as ‘offline charged’, OCS interaction has to be switched off for the rest of the session, while units still need to be recorded in the CDR written at call end to enable offline processing and billing. This can be achieved with an appropriately named ‘unlimited’ promotion bucket against which all units of the offline charged session are booked. The session counters in the CDR will show the offline charged units being booked under the selected promotion bucket name.

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