This number keeps calling and everytime I answer it hangs up and cannot be called back

Caller did not leave a message

I have gotten calls from them as well. No message left and cannot call them back. They keep changing their number though. The last 4 numbers will change. I jsut keep adding to my reject list when a new one pops up and no message is left.

dont know what this is, keeps calling, when i call it back just a verision message, this number has been disconnected?