When you have a functioning application, it is ready to be tested. Use a small group of representative callers to accomplish a set of typical tasks. It is important to make sure that the people tested are representative of the calling population. If your application is designed for customers, do not test it with your colleagues as they may have knowledge about the application that callers do not. If you know that a large proportion of your callers is over the age of 65, use test callers that are over the age of 65.