Called right at dinnertime no answer no message, blocked .......

Got a call from this number 408-389-5978: I said Hello, they didn't say anything, but I knew somebody was there. I let it go silent for about 20 sec, then hung up. Called that number back and it went to an automated voice answering system. "Hi you have reached 408-389-5978,, please leave a message after the tone"

Called didn't leave a message, called the number back and it went to a Textfree app number.
Blocked.

Called, left no message