C Programming Question

Write a program that translates an alphabetic phone number into numeric form: Enter phone number: CALLATT 2255288 In case you don't have a telephone nearby, here are the letters on the keys: 2=ABC, 3=DEF, 4-GHT, 5-JKL, 6-MNO. 7=PRS. 8 TUV. 9=WXY. If the original phone number contains nonalphabetic characters (digits or punctuation for example) leave them unchanged: Enter phone number: 1-800-COL-LECT 1-800-265-5328 You may assume that any letters entered by the user are upper case