Your telephone is for your personal use and you are not obligated to talk to anyone. Hang up if the caller does not speak or if you feel uncomfortable. Ask for the caller's identity or affiliation. If the caller gives an improper response, hang up. If the caller asks. "Who is this?" or "what number have I reached?" don't answer. Instead ask, "Who are you trying to reach?" or "What number did you call?" If the call is not legitimate, they will probably end it. If the caller persists after you have made it clear that don't' want to talk to them, the simplest response is to hang up.
REMEMBER Don't speak if you don't want to. Don't give out any information, and don't respond to questions if you don't know the caller