Why do people seem to think I am OBLIGATED to answer the phone?

"Hi, I called yesterday, you must have been out."
"No, I just didn't want to talk to you."
"Whaaat?"

We have an answering machine, so if it is important, and you leave a message, we'll get back to you. If you think it is important and we don't, it might take longer. And call waiting? Never gonna happen. If the phone is busy I must be on it.
If your a telemarketer and we actually answer, speak the language or we will make fun of you.