Initially just a vague text saying "I'll be their Sunday" so I replied 'there' as a laugh (I'm a grammar Nazi), then the number rang me, so I blocked it. Rang it back later from work phone to see what/who and it wouldn't connect properly. Think these systems send messages to see who responds, that confirms to the scammers/telemarketers? that the phone number they called is connectable, then they ring knowing they are ringing a legitimate number.