Hello there,
I always ask, "Sir/Ma'am, is the communication function turned off on your phone?", and so far it always has been. Usually they are so proud of their gadget (as I would be if I weren't holding on to my circa 1999 model, alas) that they show me the screen, explain the myriad functions, etc.
So many new functions are coming out on those things every day, I think they understand that all I can do is ask ( with a smile).