That's going to be difficult when many companies are also forcing people to use their personal phone for MFA (multi-factor authentication).

OBEY

I might work for you, but you don't fucking own me! You won't stop me from taking a piss, eating, surrendering me privacy, being able to coordinate who picks up my child, what's for dinner, or god fucking forbid an EMERGENCY that will require me to run around looking for a security guard to unlock my fucking pouch!

Your can't track my every move, every click, every eye focus! We will not abide!

They have a laptop or desktop right in front iof them connected to the internet, locking up a phone isn't going to do anything.

I thought this was a thing across the US for a while, certainly in their civil and construction fields.

Bear in mind not everyone works behind a desk or with a computer in front of them as well. The one experience I had working directly for a major American company, which was resource civil, everyone was banned from carrying phones onto site, except for a select few who had to take photos for work purposes (I was one of those).

As horrible as it sounds, the kids are so addicted to their phones you can hardly get their attention. So reluctantly, yes ban them.