This number repeatedly calls but never leaves a message. When I answer the call, no one responds.

I have the same issue. No messages, no one says anything when I answer. I don't have any collections or anything unless they are trying to use me to locate a family member or someone who used me as a reference. I never use the number they call on sites. It's only given to friends and family so that's why I think it might be in reference to someone else.