Called several times over the month.
Left a message and hung up with a sigh ...
I called back they answered no mic no words.
I believe it is spam.
They have called me back yet again since I got a new phone and it's come up as "suspected spam""

Rang twice but no mic on

Rang, but didn't leave a message. Blocked.

No one left a message. I didn't answer because I didn't recognise the number. But no message probably means a charity or similar.