dead air. don't recognize number. another web site lists this number as a scammer. blocked

Caller ID: UNKNOWN NAME  Machine answered and female, thinking she had a live victim on the line, said "Hello" twice, then, "Can you hear me OK?"  Another "Hello" and then, after realizing there was no one on the line to scam, she hung up.

3-11-17 09:41 PST CID= "Unknown Name" Found that this number called here early this morning. Very little on internet and reverse trace shows no listing for this number. I have all of area code 323 blocked so it was disconnected and logged on blocker. Have a grand day folks.

Today at 2:28 pm this number called me.  Luckily it was disconnected after one ring by my robo call stopper.

Rings 3 times hangs up , no voice mail message