Me too

Only a very few people know my number, it is listed as "unknown" and still I got a call from this number! I answered and a voice said "I'm sorry" and hung up!! Very suspicious!

Got the call.  I hung up on the recording.  I called back on a phone that is not easily identified and a recording asked if I wanted to eliminate my number from future calls.  I wanted to bait them, so I hit the Operator and it automatically hung up.

This type of call is made by calling all possible numbers in an area code, whether it is listed or not.
Eventually everybody will get this call.

Just got called, we operate a 2 person clinic (national franchaise), no one on the line, they waited a few seconds before hanging up.

got one just now - no voicemail