Does anyone have a firm policy or best practice regarding cell phone use in your shop space?

To be honest, most of the time it is not a big deal, but it kinda sucks when a volunteer's time is being wasted waiting for someone to finsish a conversation or there are people waiting to use a stand. That and it adds to general confusion in the shop when you have a "cell phone wanderer" just meandering about.

Wondering how you all handle it/don't handle it,

Thanks, Brian