Spec Sheet Preview: The Alpha Communications® AP543 adapter plates are designed specifically to cover existing oversized apartment intercom back boxes and other existing wall openings, for mounting of the IS204 or IS543 apartment intercom station(s). Once the adapter plate is affixed to the wall, you can install your IS204 or IS543 universal apartment intercom station directly onto the adapter plate, by simply pressing the station onto the front of the adapter plate. The model AP543 features a large (center) opening for wire access and you can punch or drill any mounting holes you may need to al …