The difference is due to hsitory directive of deign.
Number keys pads were first developed when calculators started being used. The numbers 0, 1, 2, and 3, are used more often than any others, thus they were put at the bottom of the keypad where they were easy to find and use. At the time the phones were all dial style.
Phone keypads are the late comers to the situation, but they grew out of the telephone dials. Due to the simple mechanics of the situation, and again the higher use numbers being first, the number 1 was the one closest to the finger stop. As people tend to put things in order and they tend to move from left to right, the dial moved to the right, clockwise. Thus the numbers counted down in an anti-clockwise direction from 1 to 0. When they decided to incorporate letter as part of the system they assigned the letter in alphabetical order to the numbers in numeric order, thus number 2 and A, B, and C assigned to it and the rest progressed from there; the number 1 was left unassigned as it was already being used for other assigned tasks within the phone system. When they moved to using number pads on phones and not dials they set them up in alpha-numeric order with A, B, and C etc at the top and number 1 prior to number 2, and the rest coming along in order. At that time no one even thought about the two even being done the same way.
So, in short, no one SWITCHED the order as there was no interaction between the design teams. What happened was each was independently developed in different ways due to different use and design imperatives.
