I have. I don't recall where I first saw it, but I do recall thinking to myself, "What's wrong with this thing? It must be broken -- it is making clicking sound

I have. I don't recall where I first saw it, but I do recall thinking to myself, "What's wrong with this thing? It must be broken -- it is making clicking sounds instead of a proper beep." Shortly after ward, the purpose of those pulse/tone switches on more modern touch-tone telephones dawned on me: they existed for backwards compatibility with especially old phone networks which didn't support touch-tone devices, only rotary-dial ones. That such networks actually existed and were still in operation didn't seem such like such a crazy idea, considering the museum piece I was holding in my hands.