public MatchType isNumberMatch(PhoneNumber firstNumberIn, PhoneNumber secondNumberIn) {
// Make copies of the phone number so that the numbers passed in are not edited.
PhoneNumber firstNumber = new PhoneNumber();
firstNumber.mergeFrom(firstNumberIn);
PhoneNumber secondNumber = new PhoneNumber();
secondNumber.mergeFrom(secondNumberIn);
// First clear raw_input, country_code_source and preferred_domestic_carrier_code fields and any
// empty-string extensions so that we can use the proto-buffer equality method.
firstNumber.clearRawInput();
firstNumber.clearCountryCodeSource();
firstNumber.clearPreferredDomesticCarrierCode();