A number I don't know from an area where I don't know anyone, so it's not going to be answered.
I did the usual quick connect & immediate disconnect w/o saying a word.
Added to the block list.

Number comes up as clean plant. Did not answer.

Did not recognize caller number or location....Did not leave a message, hung up....

Had a call from this number. I didn't pick up. It hanged up, no message left.

Caller left no message.  I called the number back ant it gave an opion to put my number in their do not call database.  I did but also blocked number on my phone.  Love my new phone.  lets me block up to 250 numbers.  A lot of good the C Reesistry does.