What is that metal plate behind the coin slot in some pay phones?
That metal plate thing appears to be part of the coin return mechanism, and it’s designed to keep coins from coming in to the phone while the coin return lever is activated. This plate appears in Western Electric, Automatic Electric, and many COCOT pay phone housings, but I have not encountered it on any Nortel pay phone models. A lot of times this plate gets stuck in the closed position and prevents coins from going into the pay phone entirely. If you find a phone like this, you should call the phone company’s repair service to get it corrected.