[Tutor] I need help on this program please

[Ashley Fowler]

This is what I have to do :

On a standard telephone, the alphabetic letters are mapped
to numbers in the following fashion:
 
A, B, AND C=2
D, E, AND F=3
G, H, AND I=4
J, K, AND L=5
M, N, AND O=6
P, Q, R, AND S=7
T, U, AND V=8
W, X, Y AND Z=9
 
Write a program that asks the user to enter a 10-character
telephone numbers in the format
 XXX-XXX-XXXX. The application should
display the telephone number with any alphabetic characters that appeared  in the original translated to their numeric
equivalent. For example, if the user enters 555-GET-FOOD the application should
display 555-438-3663.



def main():

    digits = ["2", "3", "4", "5", "6", "7", "8", "9"]
    
    numeric_phone=" "
    phone_number = input('Enter 10-Digit phone number: ')
    ch= digits[index]
    for ch in phone_number:
        if ch.isalpha():
            if ch == 'A' or ch == 'B' or ch == 'C':
              index = 0

            if ch == 'D' or ch == 'E' or ch == 'F':
                index = 1

            if ch == 'G' or ch == 'H' or ch == 'I':
                index = 2

            if ch == 'J' or ch == 'K' or ch == 'L':
                index = 3

            if ch == 'M' or ch == 'N' or ch == 'O':
                index = 4

            if ch == 'P' or ch == 'Q' or ch == 'R' or ch == 'S':
                index = 5

            if ch == 'T' or ch == 'U' or ch == 'V':
                index = 6

            if ch == 'W' or ch == 'X' or ch == 'Y' or ch == 'Z':
                index = 7
        
        numeric_phone= numberic_phone+ch
            
    print(numeric_phone)                

This is what I have so far. Can anyone make suggestions or tell me what I need to correct?
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