private void cmbPhoneNumber_KeyDown(object sender, KeyEventArgs e) { string text = cmbPhoneNumber.Text.Trim(); if (text.Length > 3) { using (ReceiptBLL recipt = new ReceiptBLL()) { this.contacts = recipt.GetContact(text); string[] stringContact = this.contacts.Select(contact => contact.PhoneNumber).ToArray(); if (stringContact.Length > 0) { cmbPhoneNumber.AutoCompleteCustomSource.AddRange(stringContact); } } } if (e.KeyCode == Keys.Enter && text.Length > 9) { this.phoneNumberValidateValue(); this.BusinessPartnerFormFieldValidation(); this.txtName.Focus(); } }