plz use this exact starter code to do the code and no scanner method and explain how the code will work

Create a function named textToNum that receives a single Phone Number (a String) as a parameter, then returns a copy of that String with all of the letters converted to numbers. Header: String textToNum( String phoneNumber) // Type code here The table below depicts which number each letter corresponds to. Example input/Output: - Input '723-647enes Output: "123-647-3937" - input 325-444-TEST Output: "325-444-8378" Output: "(653)879-8447" Notes: - Assume each letter wit be Uppercane - You may want to use the Characterisletter and/or Character isbigit methods