Most industrial companies won't allow their employees bringing cellphones or any types of gadgets that could jeopardize their security. Why? Is it because they are afraid somebody from the inside would communicate people from the outside and intrude their privacy? Whatever their reasons are, they are the ones who know. Often the company provide phone lockers to their workers.
There are even some that won't allow even valuable items inside the working premises such as wallets and other stuff so what they do is provide them with a wallet locker. Well, that can be great but I feel the employees' concerns that it get broken into and take their precious stuff away. Crimes can happen anytime of the day and anywhere. But anyway, if people would secure their wallet lockers I don't think it can easily be opened and broken into.