They called my mobile phone - left no message.

Also called my mobile, which I missed.  They left no message.  But since this now looks to be a pattern with them - and none of us posting recognizes the caller - chances are the caller is most likely a telemarketer.

Called my number 3 times within a 10 minute timeframe. They left no messages.

2 times within 5 minutes. Called back and recording says survey has expired.

Called, did not leave a message. Will be blocking this number.