Hangup, no message left

Has called my landline 4 times in the last 2 days, leaves no message.  I called back with my number blocked and the person answered: Hello Global. .  .  Many voices heard in background. Not good!

It is 3 a.m.  AventuraHQ just called me from this number..  I did not answer.

Called, left 3 seconds of silence on voicemail at 8am.

This number keeps calling me but its just a bunch of people in the back ground. So annoying that they have called 3 times already this week. I called back and it just rings.