[crazygringo]

The article doesn't make it explicit, but from the facts it presents it seems like the fundamental difference between the numeric keypad and telephone keypad is:

- With the numeric keypad, you want an extra-large 0 at the bottom that can be operated with your thumb, because zeros are so disproportionately common in real-life numbers like prices. And smaller numbers are used more than larger numbers, so you put the smaller numbers closer to the 0 so you have to reach the least, and wind up with 7-8-9 at the top.

- With dialing phone numbers, zeros aren't more frequent -- in fact they're less because phone numbers can't start with them (in the US). For local numbers, all digits 1-9 are used with approximately equal frequency. So the keypad starts with a natural numeric order of 1-2-3 at the top in reading order, and puts 0 at the bottom since it feels weird to start counting with zero (just like QWERTY keyboards start with 1, and puts 0 after 9), and because it has the special function of calling the operator.

So there seems to be an actual logic to it.