Calls numerous times a day, always hangs up, never leaves a message

calls and hangs up.... not sure what that's about

I said "hello" and got dead air.

A Pre-Spam Verification Robot. It calls to "test" if the number called (YOURS) is live, and records the gender of recipient (from listening to your voice). This data is then logged and forwarded to Boiler Room Operators who then buy "Live Numbers" and pay a premium to tailor their message/product to YOU. You picking up the call and answering with your voice is a goldmine. The Robot thanks you by hanging up without breathing into your ear piece! This is how money is made.