public string SaveInvoiceDetails(string fname, string mname, string lname, string phone, string email, string amount) { string ret = ""; PhoneValidator ph = new PhoneValidator(); if (!bll.IsValidEmailAddressOptional(email)) { ret = "Please Provide a valid email address"; } else if (!ph.PhoneNumbersOk(phone) && !phone.Equals("")) { ret = phone + " is not a valid phone number"; } else { } return(ret); }