Why do telephone keypads count from the top down, while calculators count from the bo

[wbenzoni]

I was told that they telephone keypad was inverted into order to slow down fast "dialers" (i.e. accountants and bookkeepers). Apparently there was some fear that the switches could not keep up.

All I could find was this: http://www.bellsystemmemorial.com/te...touchtone.html