Long before everyone had a mobile - I worked for a company that suddenly announced that we couldn't use office phones to make personal calls. There had never been an official policy on personal phone usage - this was an international company with a very relaxed culture. We worked hard and were successful. This edict came after the company received huge bills for international calls made after office hours to countries where we did not operate. The announcement caused a storm and the decision to prevent us making that quick call to the bank or to let someone know we were going to be late home felt petty. Eventually the rule was relaxed and then dropped but trust had been damaged. What worries me about this ruling is if it is used indiscriminately to either snoop on people or as a way to imply people are not productive.  We can not turn back the clock on the blurring of our work and personal lives in a digital age and as employers we need to talk to our teams and seek clear agreement on what is or is not expected in work time.