diff --git a/telephony/java/android/telephony/PhoneNumberUtils.java b/telephony/java/android/telephony/PhoneNumberUtils.java
index 0ecafc70b9a47309fa39db9b93741a0839444ec4..019fb7b7affe2a183be7b097a5258912e1ef2d8e 100644
--- a/telephony/java/android/telephony/PhoneNumberUtils.java
+++ b/telephony/java/android/telephony/PhoneNumberUtils.java
@@ -49,6 +49,7 @@ import com.android.telephony.Rlog;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.Arrays;
 import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -1285,6 +1286,13 @@ public class PhoneNumberUtils {
 
     private static final String SINGAPORE_ISO_COUNTRY_CODE = "SG";
 
+    private static final String[] COUNTRY_CODES_TO_FORMAT_NATIONALLY = new String[] {
+            "KR", // Korea
+            "JP", // Japan
+            "SG", // Singapore
+            "TW", // Taiwan
+    };
+
     /**
      * Breaks the given number down and formats it according to the rules
      * for the country the number is from.
@@ -1647,45 +1655,58 @@ public class PhoneNumberUtils {
             defaultCountryIso = defaultCountryIso.toUpperCase(Locale.ROOT);
         }
 
+        Rlog.v(LOG_TAG, "formatNumber: defaultCountryIso: " + defaultCountryIso);
+
         PhoneNumberUtil util = PhoneNumberUtil.getInstance();
         String result = null;
         try {
             PhoneNumber pn = util.parseAndKeepRawInput(phoneNumber, defaultCountryIso);
 
-            if (KOREA_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso) &&
-                    (pn.getCountryCode() == util.getCountryCodeForRegion(KOREA_ISO_COUNTRY_CODE)) &&
-                    (pn.getCountryCodeSource() ==
-                            PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN)) {
-                /**
-                 * Need to reformat any local Korean phone numbers (when the user is in Korea) with
-                 * country code to corresponding national format which would replace the leading
-                 * +82 with 0.
-                 */
-                result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
-            } else if (JAPAN_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso) &&
-                    pn.getCountryCode() == util.getCountryCodeForRegion(JAPAN_ISO_COUNTRY_CODE) &&
-                    (pn.getCountryCodeSource() ==
-                            PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN)) {
-                /**
-                 * Need to reformat Japanese phone numbers (when user is in Japan) with the national
-                 * dialing format.
-                 */
-                result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
-            } else if (Flags.removeCountryCodeFromLocalSingaporeCalls() &&
-                    (SINGAPORE_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso) &&
-                            pn.getCountryCode() ==
-                                    util.getCountryCodeForRegion(SINGAPORE_ISO_COUNTRY_CODE) &&
-                            (pn.getCountryCodeSource() ==
-                                    PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN))) {
-                /*
-                 * Need to reformat Singaporean phone numbers (when the user is in Singapore)
-                 * with the country code (+65) removed to comply with Singaporean regulations.
-                 */
-                result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+            if (Flags.nationalCountryCodeFormattingForLocalCalls()) {
+                if (Arrays.asList(COUNTRY_CODES_TO_FORMAT_NATIONALLY).contains(defaultCountryIso)
+                        && pn.getCountryCode() == util.getCountryCodeForRegion(defaultCountryIso)
+                        && pn.getCountryCodeSource()
+                        == PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN) {
+                    return util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+                } else {
+                    return util.formatInOriginalFormat(pn, defaultCountryIso);
+                }
             } else {
-                result = util.formatInOriginalFormat(pn, defaultCountryIso);
+                if (KOREA_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso) && (
+                        pn.getCountryCode() == util.getCountryCodeForRegion(KOREA_ISO_COUNTRY_CODE))
+                        && (pn.getCountryCodeSource()
+                        == PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN)) {
+                    /**
+                     * Need to reformat any local Korean phone numbers (when the user is in
+                     * Korea) with country code to corresponding national format which would
+                     * replace the leading +82 with 0.
+                     */
+                    result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+                } else if (JAPAN_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso)
+                        && pn.getCountryCode() == util.getCountryCodeForRegion(
+                        JAPAN_ISO_COUNTRY_CODE) && (pn.getCountryCodeSource()
+                        == PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN)) {
+                    /**
+                     * Need to reformat Japanese phone numbers (when user is in Japan) with the
+                     * national dialing format.
+                     */
+                    result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+                } else if (Flags.removeCountryCodeFromLocalSingaporeCalls() && (
+                        SINGAPORE_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso)
+                                && pn.getCountryCode() == util.getCountryCodeForRegion(
+                                SINGAPORE_ISO_COUNTRY_CODE) && (pn.getCountryCodeSource()
+                                == PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN))) {
+                    /*
+                     * Need to reformat Singaporean phone numbers (when the user is in Singapore)
+                     * with the country code (+65) removed to comply with Singaporean regulations.
+                     */
+                    result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+                } else {
+                    result = util.formatInOriginalFormat(pn, defaultCountryIso);
+                }
             }
         } catch (NumberParseException e) {
+            if (DBG) log("formatNumber: NumberParseException caught " + e);
         }
         return result;
     }