Same here, except that the payphone wasn’t so much as stolen as abandoned. (It had been installed at a rental property that was no longer being rented. They’d tried for months to get the phone company to come out and get the thing, then got sick of waiting and took it down themselves. Phone company never did get back to them.)
The coinbox itself was theft protected to prevent the person collecting it from skimming off the top. You used a key to pull it out, but there was no way to easily get the coinbox open. We think there was a collection box in their truck that you could then slot the coinbox into. It had various tabs and levers to open the coinbox and allow the money to drop into the collection box, which could only be opened back at the office.