loop and save letters in a string java

1StringBuilder phone = new StringBuilder();
2for (int i = 0; i < number.length(); i++){
3    if (Character.isLetter(number.charAt(i))){
4        phone.append(getNumber(Character.toUpperCase(number.charAt(i))));
5    }else{
6        phone.append(number.charAt(i));
7    }
8}
9
10System.out.println("Your number is " + phone.toString());

1    public static void main(String[] args){
2        Scanner input = new Scanner(System.in);
3
4            System.out.print("Enter phone number: ");
5            String number = input.nextLine();
6            String phone ="";
7
8            for (int i = 0; i < number.length(); i++){
9                if (Character.isLetter(number.charAt(i)))
10                    phone = getNumber(Character.toUpperCase(number.charAt(i)));
11                else
12                    number.charAt(i);
13            }
14            System.out.println("Your number is " + phone);              
15    }
16
17
18public static int getNumber(char uppercaseLetter){
19        if (uppercaseLetter >= 'W' && uppercaseLetter <= 'Z')
20            return 9;
21        else if (uppercaseLetter >= 'T' && uppercaseLetter < 'W')
22            return 8;
23        else if (uppercaseLetter >= 'P' && uppercaseLetter < 'T')
24            return 7;
25        else if (uppercaseLetter >= 'M' && uppercaseLetter < 'P')
26            return 6;
27        else if (uppercaseLetter >= 'J' && uppercaseLetter < 'M')
28            return 5;
29        else if (uppercaseLetter >= 'G' && uppercaseLetter < 'J')
30            return 4;
31        else if (uppercaseLetter >= 'D' && uppercaseLetter < 'G')
32            return 3;
33        else 
34            return 2;
35    }
36}