called several times.
I picked up the call today, but caller did not say anything.

Had a missed call, caller did not leave a voice message, tried returning the call but no answer and no way to know who it was.

called same time, several days in a row, no message. Called back, no answer.

Called mobile and didn't leave a message. Called back and it rang for awhile before a lady answered "Intercontinental Hotel management team"
I hung up.

Missed call,no message, rang the number back no answer, no recording sayin gthe company name etc,

Caller does not introduce who they are calling on behalf of. Calls repeatedly. when called back only first name, no name of organisation. you know what to do.

Called twice today and left no message

Called twice consecutively, didn't leave a message

Called twice today when I couldn't answer. Left no message and no answer when I called back.

It was a guy wanting to recruit me to some Crowne Hotel bonus program, claiming that I had stayed there once - I have not, ever. When I told him that I have never stayed there, he said with a rude tone "Oh yes you have" then hung up. Not impressed.

Keeps calling but doesn't leave a message