According to the judgment, text messages sent or received through a work phone “are assumed to be of a professional nature,” in other words work-related. Only the warning “personal” at the beginning of the message will stop your boss from reading the message about your private life, which, for some reason, was sent to your work phone.
All work-related messages can meanwhile be viewed and even taken to court "for legitimate reasons," especially if they contain insults, allegations of suspected fraud or breach of confidentiality .... http://rt.com