FIG. 2 shows an example of our case or wall-mount housing 30, here holding the control box unit 10, and comprising a lower or back main housing component 32 and a lid or cap 34 that fits into (or onto) the lower component 32 and also fits over the unit 10 to hold it in place. The cap has a circular opening or window 38 to provide access to the keys or buttons of the key pad 12. Here, the diameter of the opening 38 of cap portion 34 is slightly smaller than the top of the shell 14 of the control unit 10. The main housing component 32 has a generally cylindrical wall 36 with perforations 37 around its lower periphery to permit ventilation and sound transmission. Favorably, a ring of a plastic foam or other yielding resilient material, discussed below, may be present inside the upper part of the cap portion 34 to serve as means for retaining the control unit 10 and keeping it held at a steady position inside the case or housing 30. Other equivalent retaining means are available and could be used instead. In this embodiment, the window 38 is open, but in other embodiments there may be a clear membrane at the opening that allows touch-access to the key pad 12 or other user interface provided on the control unit.