steven r: You're right about UC 10. Now that you mention it I realize that I've been happily punching in "10" and the TR16A was ignoring the "1" and only hearing the last digit "0". Another theory bites the dust.
As to audible feedback. I've been using X-10 telephone transponders since they first came out and between the first dedicated remote for them and POT set control for the later ones have always been used to hearing some kind of tone when I pushed a button. My more recent, small, cell phones haven't produced a tone on a button push unless I programed them to and it took me a while to pay attention to the screen to see what I was doing. No practical problem now, since the learning curve is long over, but I still miss it for this application.