c sharp programing language

namespace _11_RegularExpressions
{
    class Class1
    {
        [STAThread]
        static void Main(string[] args)
        {
            Regex phoneExp = new Regex(@"^(234[7|8][0|1][2-9])([0-9]{7}$");
            string input;
            Console.Write("Enter a phone number: ");
            input = Console.ReadLine();
            while (phoneExp.Match(input).Success == false)
            {
                Console.WriteLine("Invalid input. Try again.");
                Console.Write("Enter a phone number: ");
                input = Console.ReadLine();
            }
            Console.WriteLine("Validated!");