they keep calling and either hang up when answered or say nothing then hang up

I redailed the number and the recording stated that this number had been disconnected.

Caller was looking for a friend to talk to.

Called called after 8:00 p.m. Unknown research group calling my cell phone.

Repeatedly calls. I finally answered the call and they were trying to extend a car warranty. I told him nicely that we weren't interested and to stop calling. He asked why and kept trying to push. Finally I had to get VERY rude about it and he laughed in my face. Told them if they called again we'd report them to the proper authorities.