Number called my cell number at 11:22 am on a Saturday. I answered and no one picked up on the other end. After 8 seconds the call was disconnected. I have seen this number before but it has been awhile and will block it again.
It sounds like you keep picking up and expecting someone to be there, and I can' help but wonder why. Try picking up and hanging up immediately. Some robodialers will register a "live" phone line whenever the word "hello" is recognized. Since you know this is the number they call from. don't answer it any more or answer and hang up immediately without saying anything. I know it's a big pain you-know-where because I've been there, but eventually they will stop if you stop interacting with them.