using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {                       

        Console.WriteLine(ValidaCelular("51991012434"));

    }

​

    public static bool ValidaCelular(string number)

       {

           return Regex.Match(number, @"^\(?(?:[14689][1-9]|2[12478]|3[1234578]|5[1345]|7[134579])\)? ?(?:[2-8]|9[1-9])[0-9]{3}\-?[0-9]{4}$").Success;

       }        

}