Did You Ever Think Why Numbers On Phones And Calculators Are Opposite?

Have you ever thought why the numbers are written in different style in a phone and in a calculator? Why this pattern was followed? Why 7-8-9 on the top row of a calculator and 1-2-3 on the phone? Do you think there must be any reason behind it? Sounds interesting right? Read the following article to find your answer. 

In The Early 1900s Us Invented The Rotary Telephone

In The Early 1900s Us Invented The Rotary Telephone
The numbers on the telephone had holes from number 1 to 9 and then 0 after 9.