did not leave a message , but if you call the number back it gives you the option to have your number  taken off of there call list

No message; I disconnected call before answering machine could pick up (call from Gaithersburg, MD

Got call on my cell.  Didn't recognize number so I did NOT pick up.  No message was left, so it must  NOT have been important!
FYI-  You should never pick up a suspected robocall/scammer; even to either "mess with them" or to tell them to take your name/number off-their-list.  The only thing that is accomplished is that you CONFIRM to the computer-dialing-program that your number is valid and can now be bundled and SOLD TO OTHER TELEMARKETERS!

call to home.  cid Gaithersburg MD.  mistakenly answered, silence.

Called my cell phone. I answered. Nothing but silence