Eddy, thank you.
Chris, on this particular occasion, it wasn't ONLY due to fuel truck... the pax had, while on his phone, started to drift toward another aircraft on an adjacent bay, which was being attended to by ground service equip. Whether the phone would affect the fuel truck or not, I certainly didn't want him stepping in front of a catering truck!!!!
And, while *I* may know phones may not necessarily cause any harm, it's the rule on our tarmac and so I enforce it. Especially when said pax are regular travellers and should know better!! And not only for the fuel truck reason, but again, for concentration and safety. If one pax is on phone, another may think 'well you're not supposed to be on the phone, but I guess he is, so i may as well have a smoke....'
So, any pax on one of our aircraft ANYWHERE should always be told 'phone off'....!