2019-6: Telephone Names

1	2ABC	3DEF
4GHI	5JKL	6MNO
7PQRS	8TUV	9WXYZ
*	0	#

Some telephone keypads have letters of the alphabet embossed on their keytops.

Some people like to remember phone numbers by converting them to an alphanumeric form using one of the letters on the corresponding key.

For example, in the keypad shown, "ALSMITH" would correspond to the number 257-6484 and "1DYALOGBEST" would correspond to 1-392-564-2378.

Write code that takes a character vector argument that consists of digits and uppercase letters and returns an integer vector of the corresponding digits on the keypad.