diff --git i/src/phonenumberutil.js w/src/phonenumberutil.js
index 7569eee..2b20e4a 100644
--- i/src/phonenumberutil.js
+++ w/src/phonenumberutil.js
@@ -2972,7 +2972,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.getCountryCodeForRegion =
  *     calling code for.
  * @return {number} the country calling code for the region denoted by
  *     regionCode.
- * @throws {Error} if the region is invalid
+ * @throws {string} if the region is invalid
  * @private
  */
 i18n.phonenumbers.PhoneNumberUtil.prototype.getCountryCodeForValidRegion_ =
@@ -2981,7 +2981,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.getCountryCodeForValidRegion_ =
   /** @type {i18n.phonenumbers.PhoneMetadata} */
   var metadata = this.getMetadataForRegion(regionCode);
   if (metadata == null) {
-    throw new Error('Invalid region code: ' + regionCode);
+    throw 'Invalid region code: ' + regionCode;
   }
   return metadata.getCountryCodeOrDefault();
 };
@@ -3379,7 +3379,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.maybeExtractCountryCode =
       i18n.phonenumbers.PhoneNumber.CountryCodeSource.FROM_DEFAULT_COUNTRY) {
     if (fullNumber.getLength() <=
         i18n.phonenumbers.PhoneNumberUtil.MIN_LENGTH_FOR_NSN_) {
-      throw new Error(i18n.phonenumbers.Error.TOO_SHORT_AFTER_IDD);
+      throw i18n.phonenumbers.Error.TOO_SHORT_AFTER_IDD;
     }
     /** @type {number} */
     var potentialCountryCode = this.extractCountryCode(fullNumber,
@@ -3391,7 +3391,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.maybeExtractCountryCode =
 
     // If this fails, they must be using a strange country calling code that we
     // don't recognize, or that doesn't exist.
-    throw new Error(i18n.phonenumbers.Error.INVALID_COUNTRY_CODE);
+    throw i18n.phonenumbers.Error.INVALID_COUNTRY_CODE;
   } else if (defaultRegionMetadata != null) {
     // Check to see if the number starts with the country calling code for the
     // default region. If so, we remove the country calling code, and do some
@@ -3742,7 +3742,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseAndKeepRawInput =
   if (!this.isValidRegionCode_(defaultRegion)) {
     if (numberToParse.length > 0 && numberToParse.charAt(0) !=
         i18n.phonenumbers.PhoneNumberUtil.PLUS_SIGN) {
-      throw new Error(i18n.phonenumbers.Error.INVALID_COUNTRY_CODE);
+      throw i18n.phonenumbers.Error.INVALID_COUNTRY_CODE;
     }
   }
   return this.parseHelper_(numberToParse, defaultRegion, true, true);
@@ -3801,10 +3801,10 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseHelper_ =
     function(numberToParse, defaultRegion, keepRawInput, checkRegion) {
 
   if (numberToParse == null) {
-    throw new Error(i18n.phonenumbers.Error.NOT_A_NUMBER);
+    throw i18n.phonenumbers.Error.NOT_A_NUMBER;
   } else if (numberToParse.length >
       i18n.phonenumbers.PhoneNumberUtil.MAX_INPUT_STRING_LENGTH_) {
-    throw new Error(i18n.phonenumbers.Error.TOO_LONG);
+    throw i18n.phonenumbers.Error.TOO_LONG;
   }
 
   /** @type {!goog.string.StringBuffer} */
@@ -3813,14 +3813,14 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseHelper_ =
 
   if (!i18n.phonenumbers.PhoneNumberUtil.isViablePhoneNumber(
       nationalNumber.toString())) {
-    throw new Error(i18n.phonenumbers.Error.NOT_A_NUMBER);
+    throw i18n.phonenumbers.Error.NOT_A_NUMBER;
   }
 
   // Check the region supplied is valid, or that the extracted number starts
   // with some sort of + sign so the number's region can be determined.
   if (checkRegion &&
       !this.checkRegionForParsing_(nationalNumber.toString(), defaultRegion)) {
-    throw new Error(i18n.phonenumbers.Error.INVALID_COUNTRY_CODE);
+    throw i18n.phonenumbers.Error.INVALID_COUNTRY_CODE;
   }
 
   /** @type {i18n.phonenumbers.PhoneNumber} */
@@ -3850,7 +3850,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseHelper_ =
     countryCode = this.maybeExtractCountryCode(nationalNumberStr,
         regionMetadata, normalizedNationalNumber, keepRawInput, phoneNumber);
   } catch (e) {
-    if (e.message == i18n.phonenumbers.Error.INVALID_COUNTRY_CODE &&
+    if (e == i18n.phonenumbers.Error.INVALID_COUNTRY_CODE &&
         i18n.phonenumbers.PhoneNumberUtil.LEADING_PLUS_CHARS_PATTERN_
             .test(nationalNumberStr)) {
       // Strip the plus-char, and try again.
@@ -3888,7 +3888,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseHelper_ =
   }
   if (normalizedNationalNumber.getLength() <
       i18n.phonenumbers.PhoneNumberUtil.MIN_LENGTH_FOR_NSN_) {
-    throw new Error(i18n.phonenumbers.Error.TOO_SHORT_NSN);
+    throw i18n.phonenumbers.Error.TOO_SHORT_NSN;
   }
 
   if (regionMetadata != null) {
@@ -3913,11 +3913,11 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.parseHelper_ =
   var lengthOfNationalNumber = normalizedNationalNumberStr.length;
   if (lengthOfNationalNumber <
       i18n.phonenumbers.PhoneNumberUtil.MIN_LENGTH_FOR_NSN_) {
-    throw new Error(i18n.phonenumbers.Error.TOO_SHORT_NSN);
+    throw i18n.phonenumbers.Error.TOO_SHORT_NSN;
   }
   if (lengthOfNationalNumber >
       i18n.phonenumbers.PhoneNumberUtil.MAX_LENGTH_FOR_NSN_) {
-    throw new Error(i18n.phonenumbers.Error.TOO_LONG);
+    throw i18n.phonenumbers.Error.TOO_LONG;
   }
   this.setItalianLeadingZerosForPhoneNumber_(
       normalizedNationalNumberStr, phoneNumber);
@@ -4041,7 +4041,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.isNumberMatch =
       firstNumber = this.parse(
           firstNumberIn, i18n.phonenumbers.PhoneNumberUtil.UNKNOWN_REGION_);
     } catch (e) {
-      if (e.message != i18n.phonenumbers.Error.INVALID_COUNTRY_CODE) {
+      if (e != i18n.phonenumbers.Error.INVALID_COUNTRY_CODE) {
         return i18n.phonenumbers.PhoneNumberUtil.MatchType.NOT_A_NUMBER;
       }
       // The first number has no country calling code. EXACT_MATCH is no longer
@@ -4085,7 +4085,7 @@ i18n.phonenumbers.PhoneNumberUtil.prototype.isNumberMatch =
           secondNumberIn, i18n.phonenumbers.PhoneNumberUtil.UNKNOWN_REGION_);
       return this.isNumberMatch(firstNumberIn, secondNumber);
     } catch (e) {
-      if (e.message != i18n.phonenumbers.Error.INVALID_COUNTRY_CODE) {
+      if (e != i18n.phonenumbers.Error.INVALID_COUNTRY_CODE) {
         return i18n.phonenumbers.PhoneNumberUtil.MatchType.NOT_A_NUMBER;
       }
       return this.isNumberMatch(secondNumberIn, firstNumber);