For me, it was for the local newspaper. They want to get you to subscribe or offer to expand your current service for free.

Don't know who they are, they keep calling.  Do they really think I will answer if they won't leave a message??

They kept calling me these days. I've been ignoring since I don't recognize the number but when I picked to see who's calling they won't say anything and hung up... I picked up twice and they hung up both times.  Very annoying.

Didn't answer the call.  They didn't leave a message.  I never answer numbers I don't recognize.