Spec Sheet Preview: The Alpha Communications® SF154A push type emergency station is used to initiate system emergency signals. Signaling an emergency is accomplished by depressing the locking push button switch located at the center of the faceplate to the "IN" position. In this position, the button will appear Red. Depressing the push button again cancels the call and the Red color disappears and turns Black. The signal cannot be cancelled except at the point of origin.