Why didnt you just keep your phone in the car then?

Wow unfair dismissal case right there :)

I recommend checking with a lawyer, you might be able to sue over this

do you work in an airport where they stripsearch and fondle your balls?

Invasion of personal property. Report him.

Keep it in your trunk... There are rules for a reason.

for all the people talking about unfair dismissal and sueing, OP doesn't say what state they're in, but a lot of states employers can fire people for any reason that doesn't have to do with a protected class. employees rights have been eroded over the years along with union powers

Why didn't you just leave it in your car or at home? they can't punish you for "not having" a cell phone on the property at all.

I worked in a Corporate Loss Prevention/Operations Management position for 4 years. Unfortunately there is no law concerning lockers and security requirements with regards to personal items. The messed up thing is that from a "Loss Prevention" standpoint, Managers/Supervisors are required to do locker checks on a daily basis and if a locker has no lock, they are allowed to open it without asking permission from any company employees. Essentially leaving your goods there for the taking. The only thing to do in this case is keep your phone in your car at that time.

That can't fire you for that. Legally that is. I'd say file a lawsuit or at least threaten one