calculate the best available tariff offer for customers based on their current bill and future needs

best means the top-ranked offer based on the configured business rules. Usually this means the cheapest offer, but that can be constrained by rules such as minimum and maximum savings or value thresholds.

available means the set of tariffs selected from those which match business rules for the customer. Typical business rules are to select only 'own' tariffs, or to constrain which tariffs a customer can migrate to based on position within contract, segment and value score.

tariff offer means a published tariff plan or set of complementary tariff plans, plus any discretionary add-on products

current bill means the actual customer behaviour, in the form of service usage, over a recent period. Usually this is captured from a set of the latest bill data, for example the previous 3 months.

future needs means whatever changes the current behaviour are projected for the near future. For example, the customer is growing or shrinking, or its business activities are changing, or its service usage mix is changing