There are two states for an application, the Development and Production states :
When you create a new app, it starts in the development state.
In this state, you can develop your code, and test the application, having access to full functionality, but with a mock-up dataset. This dataset is dedicated to each application. Therefore, if you have more than one application, your tests won't affect each other. Furthermore, with this dataset, you can execute transactions, without the fear of making a mistake. In this mock-up dataset, customers and their products are predefined.
When the development phase is completed, you can request an upgrade of your application from development to production.
A representative from the bank will contact you, in order to arrange the required paperwork. When approved, your application will be live. From now on, all calls will have access to live data, and the customers that will use it are the real ones.