using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        string telefoneCompleto = FormatarTelefone("1132053755");

        string ddd = telefoneCompleto.Substring(0, 2);

        string telefone = telefoneCompleto.Substring(telefoneCompleto.Length - 9);

        Console.WriteLine("DDD:" + ddd);

        Console.WriteLine("TELEFONE:" + telefone);

    }

    public static string FormatarTelefone(string str)

        {

            StringBuilder sb = new StringBuilder();

            str = str.Replace("+55", "");

            foreach (char c in str)

            {

                if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '.' || c == '_')

                {

                    sb.Append(c);

                }

            }

            if (sb.ToString().StartsWith("0"))

                sb = sb.Remove(0, 1);

            if (sb.Length < 11)

                if (sb.Length < 2)

                    return sb.ToString().PadLeft(11, '9');

                else

                    return sb.ToString().Substring(0,2) + sb.ToString().PadLeft(9, '9');

​

            return sb.ToString();

        }

}