It is a standard residential doorbell with the dual metal bars. Depressing the button provides the "ding" and releasing the button provides the "dong." I have seen some interfaces such as the Russound DIM-1 and Niles DBI, but these appear to need to be placed after the bell and trigger from contact closure. I only have access to the wires prior to the doorbell right after the transformer which are under constant 16VAC.