The CIO has assigned your team the task of developing software that supports a voice mail system with a web front end. The telephone switchboard system will transfer callers who want to leave voice mail to the voice mail system. The voice mail system will save messages with appropriate meta-data describing the message. Mailbox owners can check for messages using a web browser, and can hear messages played on their PC's speakers.

As one step of the development process, your team should create a set of classes that model the problem domain. Later you will worry about software design specifications; for now, you are concerned about the analysis of the problem. You need to create classes to represent the data and behaviors of the "real world" rather than of the computer system.