TRIVIAL PURSUITS: Which Two Letters Are Not on Standard Telephone Keypads?

As you all know, landline telephone and cellphone keypads have letters associated with the numbers.
By PS

You may look at your cellphone keypad and see all letters in the alphabet represented under a number.

 

However, that is not the North American standard for telephones? Typically, two letters are missing.

 

Which two letters are missing from North American standard telephone keypads?

 

They are “Q” and “Z.”