convert int to string

hi guys
how can i convert this code to  string to save phone number
   SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());         SqlCommand cmd = new SqlCommand();         cmd.Connection = con;         cmd.CommandType = CommandType.StoredProcedure;         cmd.CommandText = string.Format("insert1");         SqlParameter PID = new SqlParameter("@NewID", DbType.Int32);         PID.Direction = ParameterDirection.Output;         cmd.Parameters.Add(PID);
cmd.Parameters.AddWithValue("@name", TextBox30.Text);
cmd.Parameters.AddWithValue("@mob2", T ...