Received a call with no message.

Same here, called my cell, no message.

Immediate hangup. No message.

This NEW scam number just called my very private cell phone #.... I answer, yell "remove this call from data bases", then leave on the desk while I continue working; the call disconnected after about 20secs.
Just a little FYI- I find that saving up a bunch of numbers, and reporting them all at once to Do Not Call (usually) suspends all Unwanted/SPAM calls for a couple of weeks.  Hey it's something.

Called, said nothing, hung up after 10 seconds (Santa Monica like other people on here said). This is most likely some kind of crawler that dials a million numbers and finds out which ones pick up so they can further troll you down the road. Best to not pick up unknown numbers (unlike me).