In the glossary, which of the following is NOT listed as a phone number type?

• A. Internal
• B. External
• C. Callback
• D. Fax

Answer: (D)

Think of the glossary as organizing numbers by how they’re used to reach someone. Internal means dialing an inside extension, external points to outside lines, and callback designates a number saved for returning a call. These categories describe the role of the number in communication.

Fax, while it uses a phone line, isn’t a type that describes how you reach someone. It’s a device or service (a fax transmission method) rather than a category for a phone number’s purpose. That’s why fax isn’t listed as a phone number type in the glossary.