Why does “ABC” begin on the number two on the phone instead of one?
The answer to your question appears in the 2nd paragraph.
on an old phone i have here the letters Q & Z are on A
but now they start from 2 and the keys go like this
ABC DEF GHI JKL MNO PQRS TUV WXYZ
2 3 4 5 6 7 8 9