1. eC Calling Cards

2. Calling cards are a relatively recent phenomenon. The premise is fairly simple: an entrepreneur buys a large block of billable service minutes from a larger telecommunications company. The entrepreneur then re-sells the time in smaller blocks, at a profit.

3. A brief examination of a calling card operation yields the surprising result that it is, essentially, a data management problem with the objective of keeping track of changes to these small blocks of allocated time.

4. In its simplest form, the database of calling cards might retain only the ID numbers (sometimes also called PIN codes) and the balance remaining in that account. The company would also need to maintain a database of country codes, along with the associated rates and charges.

5. Card record Card ID Balance Expiration Date

6. Country record Country ID Connection fee PerMinuteFee

7. Most calling card systems are of the type described above, such that when the original balance is exhausted the card is no longer valid and is discarded.

8. However, some systems provide the option for the user to recharge the card, either by phone or through the web. By doing so, it is possible to establish a connection between a particular card and its user, and, conceivably, the transaction history of its user.

9. The database overview slides contain links to the full database schema for “disposable” calling cards as well as “rechargeable” cards, along with a working JSP servlet that allows cards to be configured and re- charged.