... if you haven't remembered to put it in airplane mode.

Manchester United v Liverpool: Jose Mourinho answers reporter's phone - BBC Sport (http://www.bbc.co.uk/sport/football/38609575)
Manchester United manager Jose Mourinho answers a reporter's phone in the middle of his news conference previewing Sunday's match against Liverpool.

(Apologies to those who may not be able to load the video).

I sometimes hand off my iPhone 6S Plus to clients to go snag certain shots when I am unable to move away from a setup, and I always set it to airplane mode and 4K. The latter to keep any potential phone calls or texts from showing up and the former to readjust the composition that may not be the best.