public void TestIsValidPhoneNumber()
 {
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(internalNumber), NumberStringType.INTERNAL);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(externalNumber), NumberStringType.EXTERNAL);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(noPossibleNumber), NumberStringType.NOT_POSSIBLE);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(noValidNumber), NumberStringType.NOT_VALID);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(externalWithSymbols), NumberStringType.EXTERNAL);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(externalGerman), NumberStringType.EXTERNAL);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(externalAustria), NumberStringType.EXTERNAL);
     Assert.AreEqual(NumberStringUtils.IsValidPhoneNumber(externalAustria2), NumberStringType.EXTERNAL);
 }
        /// <summary>
        /// Checks if the content of the clipboard can be used as a number and sets the current number if so.
        /// </summary>
        private void ProcessClipboardContent()
        {
            NumberStringType type = NumberStringUtils.IsValidPhoneNumber(_currentClipboardContent);

            switch (type)
            {
            case NumberStringType.NOT_POSSIBLE:
                // Do nothing because the clipboard does not contain a number
                break;

            case NumberStringType.NOT_VALID:
                // Do nothing because the content of the clipboard is not a valid number
                // Here the option could be implementet, to inform the user about the fact he has copied a possible but not valid number.
                // It could be a valid number in another country. This could be checked.
                break;

            default:
                CurrentNumber = new Number(NumberStringUtils.FormatNumberString(_currentClipboardContent), type);
                Clipboard.Clear(); // Bugfix to stop randomly appearing balllon tipps if you copy a valid external/internal number
                break;
            }
        }