Index: apps/app_voicemail.c
===================================================================
--- apps/app_voicemail.c	(revision 201533)
+++ apps/app_voicemail.c	(working copy)
@@ -6744,7 +6744,7 @@
 		res = ast_say_date_with_format(chan, t, AST_DIGIT_ANY, chan->language, "'vm-received' q  H 'digits/kai' M ", NULL);
 	else if (!strcasecmp(chan->language,"pt_BR"))
 		res = ast_say_date_with_format(chan, t, AST_DIGIT_ANY, chan->language, "'vm-received' Ad 'digits/pt-de' B 'digits/pt-de' Y 'digits/pt-as' HM ", NULL);
-	else if (!strcasecmp(chan->language,"tw"))      /* CHINESE (Taiwan) syntax */
+	else if (!strncasecmp(chan->language, "zh", 2)) /* CHINESE (Taiwan) syntax */
 		res = ast_say_date_with_format(chan, t, AST_DIGIT_ANY, chan->language, "qR 'vm-received'", NULL);		
 	else {
 		res = ast_say_date_with_format(chan, t, AST_DIGIT_ANY, chan->language, "'vm-received' q 'digits/at' IMp", NULL);
@@ -8101,7 +8101,7 @@
 }
 
 /* CHINESE (Taiwan) syntax */
-static int vm_intro_tw(struct ast_channel *chan, struct vm_state *vms)
+static int vm_intro_zh(struct ast_channel *chan, struct vm_state *vms)
 {
 	int res;
 	/* Introduce messages they have */
@@ -8180,8 +8180,8 @@
 		return vm_intro_no(chan, vms);
 	} else if (!strcasecmp(chan->language, "ru")) { /* RUSSIAN syntax */
 		return vm_intro_multilang(chan, vms, "n");
-	} else if (!strcasecmp(chan->language, "tw")) { /* CHINESE (Taiwan) syntax */
-		return vm_intro_tw(chan, vms);
+	} else if (!strncasecmp(chan->language, "zh", 2)) { /* CHINESE (Taiwan) syntax */
+		return vm_intro_zh(chan, vms);
 	} else if (!strcasecmp(chan->language, "ua")) { /* UKRAINIAN syntax */
 		return vm_intro_multilang(chan, vms, "n");
 	} else if (!strcasecmp(chan->language, "he")) { /* HEBREW syntax */
@@ -8271,7 +8271,7 @@
 	return res;
 }
 
-static int vm_instructions_tw(struct ast_channel *chan, struct ast_vm_user *vmu, struct vm_state *vms,  int skipadvanced, int in_urgent)
+static int vm_instructions_zh(struct ast_channel *chan, struct ast_vm_user *vmu, struct vm_state *vms,  int skipadvanced, int in_urgent)
 {
 	int res = 0;
 	/* Play instructions and wait for new command */
@@ -8297,8 +8297,8 @@
 
 static int vm_instructions(struct ast_channel *chan, struct ast_vm_user *vmu, struct vm_state *vms, int skipadvanced, int in_urgent)
 {
-	if (vms->starting && !strcasecmp(chan->language, "tw")) { /* CHINESE (Taiwan) syntax */
-		return vm_instructions_tw(chan, vmu, vms, skipadvanced, in_urgent);
+	if (vms->starting && !strncasecmp(chan->language, "zh", 2)) { /* CHINESE (Taiwan) syntax */
+		return vm_instructions_zh(chan, vmu, vms, skipadvanced, in_urgent);
 	} else {					/* Default to ENGLISH */
 		return vm_instructions_en(chan, vmu, vms, skipadvanced, in_urgent);
 	}
@@ -8752,7 +8752,7 @@
  *
  * \return zero on success, -1 on error.
  */
-static int vm_browse_messages_tw(struct ast_channel *chan, struct vm_state *vms, struct ast_vm_user *vmu)
+static int vm_browse_messages_zh(struct ast_channel *chan, struct vm_state *vms, struct ast_vm_user *vmu)
 {
 	int cmd=0;
 
@@ -8793,8 +8793,8 @@
 		return vm_browse_messages_pt(chan, vms, vmu);
 	} else if (!strcasecmp(chan->language, "gr")){
 		return vm_browse_messages_gr(chan, vms, vmu);   /* GREEK */
-	} else if (!strcasecmp(chan->language, "tw")){
-		return vm_browse_messages_tw(chan, vms, vmu);   /* CHINESE (Taiwan) */
+	} else if (!strncasecmp(chan->language, "zh", 2)) {
+		return vm_browse_messages_zh(chan, vms, vmu);   /* CHINESE (Taiwan) */
 	} else if (!strcasecmp(chan->language, "he")) {
 		return vm_browse_messages_he(chan, vms, vmu);   /* HEBREW */
 	} else {	/* Default to English syntax */
Index: UPGRADE.txt
===================================================================
--- UPGRADE.txt	(revision 201531)
+++ UPGRADE.txt	(working copy)
@@ -25,6 +25,12 @@
   Two applications previously provided by res_indications, PlayTones and
   StopPlayTones, have been moved into a new module, app_playtones.
 
+* Support for Taiwanese was incorrectly supported with the "tw" language code.
+  In reality, the "tw" language code is reserved for the Twi language, native
+  to Ghana.  If you were previously using the "tw" language code, you should
+  switch to using either "zh" (for Mandarin Chinese) or "zh_TW" for Taiwan
+  specific localizations.
+
 From 1.6.0.1 to 1.6.1:
 
 * The ast_agi_register_multiple() and ast_agi_unregister_multiple()
@@ -114,3 +120,10 @@
   func_sprintf, and is no longer included in func_strings. If you use this
   function and do not use 'autoload=yes' in modules.conf, you will need
   to explicitly load func_sprintf for it to be available.
+
+* Support for Taiwanese was incorrectly supported with the "tw" language code.
+  In reality, the "tw" language code is reserved for the Twi language, native
+  to Ghana.  If you were previously using the "tw" language code, you should
+  switch to using either "zh" (for Mandarin Chinese) or "zh_TW" for Taiwan
+  specific localizations.
+
Index: main/say.c
===================================================================
--- main/say.c	(revision 201531)
+++ main/say.c	(working copy)
@@ -343,7 +343,7 @@
 static int ast_say_number_full_pl(struct ast_channel *chan, int num, const char *ints, const char *language, const char *options, int audiofd, int ctrlfd);
 static int ast_say_number_full_pt(struct ast_channel *chan, int num, const char *ints, const char *language, const char *options, int audiofd, int ctrlfd);
 static int ast_say_number_full_se(struct ast_channel *chan, int num, const char *ints, const char *language, const char *options, int audiofd, int ctrlfd);
-static int ast_say_number_full_tw(struct ast_channel *chan, int num, const char *ints, const char *language, int audiofd, int ctrlfd);
+static int ast_say_number_full_zh(struct ast_channel *chan, int num, const char *ints, const char *language, int audiofd, int ctrlfd);
 static int ast_say_number_full_gr(struct ast_channel *chan, int num, const char *ints, const char *language, int audiofd, int ctrlfd);
 static int ast_say_number_full_ru(struct ast_channel *chan, int num, const char *ints, const char *language, const char *options, int audiofd, int ctrlfd);
 static int ast_say_number_full_ge(struct ast_channel *chan, int num, const char *ints, const char *language, const char *options, int audiofd, int ctrlfd);
@@ -379,7 +379,7 @@
 static int ast_say_date_with_format_nl(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
 static int ast_say_date_with_format_pl(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
 static int ast_say_date_with_format_pt(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
-static int ast_say_date_with_format_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
+static int ast_say_date_with_format_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
 static int ast_say_date_with_format_gr(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
 static int ast_say_date_with_format_th(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone);
 
@@ -389,7 +389,7 @@
 static int ast_say_time_nl(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_time_pt(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_time_pt_BR(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
-static int ast_say_time_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
+static int ast_say_time_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_time_gr(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_time_ge(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_time_hu(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
@@ -402,7 +402,7 @@
 static int ast_say_datetime_nl(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_datetime_pt(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_datetime_pt_BR(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
-static int ast_say_datetime_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
+static int ast_say_datetime_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_datetime_gr(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_datetime_ge(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
 static int ast_say_datetime_hu(struct ast_channel *chan, time_t t, const char *ints, const char *lang);
@@ -459,8 +459,8 @@
 	   return(ast_say_number_full_pt(chan, num, ints, language, options, audiofd, ctrlfd));
 	} else if (!strcasecmp(language, "se") ) {	/* Swedish syntax */
 	   return(ast_say_number_full_se(chan, num, ints, language, options, audiofd, ctrlfd));
-	} else if (!strcasecmp(language, "tw") || !strcasecmp(language, "zh") ) {	/* Taiwanese / Chinese syntax */
-	   return(ast_say_number_full_tw(chan, num, ints, language, audiofd, ctrlfd));
+	} else if (!strncasecmp(language, "zh", 2) ) {	/* Taiwanese / Chinese syntax */
+	   return(ast_say_number_full_zh(chan, num, ints, language, audiofd, ctrlfd));
 	} else if (!strcasecmp(language, "gr") ) {	/* Greek syntax */
 	   return(ast_say_number_full_gr(chan, num, ints, language, audiofd, ctrlfd));
 	} else if (!strcasecmp(language, "ru") ) {	/* Russian syntax */
@@ -2239,8 +2239,8 @@
 	return res;
 }
 
-/*! \brief  ast_say_number_full_tw: Taiwanese / Chinese syntax */
-static int ast_say_number_full_tw(struct ast_channel *chan, int num, const char *ints, const char *language, int audiofd, int ctrlfd)
+/*! \brief  ast_say_number_full_zh: Taiwanese / Chinese syntax */
+static int ast_say_number_full_zh(struct ast_channel *chan, int num, const char *ints, const char *language, int audiofd, int ctrlfd)
 {
 	int res = 0;
 	int playh = 0;
@@ -2315,7 +2315,7 @@
 					last_length = strlen(buf);
 					num -= ((num / 1000) * 1000);
 				} else if (num < 100000000) { /* 100,000,000 */
-						res = ast_say_number_full_tw(chan, num / 10000, ints, language, audiofd, ctrlfd);
+						res = ast_say_number_full_zh(chan, num / 10000, ints, language, audiofd, ctrlfd);
 						if (res)
 							return res;
 						snprintf(buf, 10, "%d", num);
@@ -2325,7 +2325,7 @@
 						snprintf(fn, sizeof(fn), "digits/wan");
 				} else {
 					if (num < 1000000000) { /* 1,000,000,000 */
-						res = ast_say_number_full_tw(chan, num / 100000000, ints, language, audiofd, ctrlfd);
+						res = ast_say_number_full_zh(chan, num / 100000000, ints, language, audiofd, ctrlfd);
 						if (res)
 							return res;
 						snprintf(buf, 10, "%d", num);
@@ -3425,8 +3425,8 @@
 		return (ast_say_date_with_format_pl(chan, t, ints, lang, format, tzone));
 	} else if (!strcasecmp(lang, "pt") || !strcasecmp(lang, "pt_BR")) {	/* Portuguese syntax */
 		return (ast_say_date_with_format_pt(chan, t, ints, lang, format, tzone));
-	} else if (!strcasecmp(lang, "tw") || !strcasecmp(lang, "zh") ) {	/* Taiwanese / Chinese syntax */
-		return (ast_say_date_with_format_tw(chan, t, ints, lang, format, tzone));
+	} else if (!strncasecmp(lang, "zh", 2) ) {	/* Taiwanese / Chinese syntax */
+		return (ast_say_date_with_format_zh(chan, t, ints, lang, format, tzone));
 	} else if (!strcasecmp(lang, "th") ) {	/* Thai syntax */
 		return (ast_say_date_with_format_th(chan, t, ints, lang, format, tzone));
 	} else if (!strcasecmp(lang, "gr") ) {	/* Greek syntax */
@@ -5743,7 +5743,7 @@
 }
 
 /* Taiwanese / Chinese syntax */
-int ast_say_date_with_format_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone)
+int ast_say_date_with_format_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang, const char *format, const char *tzone)
 {
 	struct timeval when = { t, 0 };
 	struct ast_tm tm;
@@ -5935,7 +5935,7 @@
 						/* Yesterday */
 						res = wait_file(chan, ints, "digits/yesterday", lang);
 					} else {
-						res = ast_say_date_with_format_tw(chan, t, ints, lang, "YBdA", tzone);
+						res = ast_say_date_with_format_zh(chan, t, ints, lang, "YBdA", tzone);
 					}
 				}
 				break;
@@ -5960,14 +5960,14 @@
 						res = wait_file(chan, ints, "digits/yesterday", lang);
 					} else if (beg_today - 86400 * 6 < t) {
 						/* Within the last week */
-						res = ast_say_date_with_format_tw(chan, t, ints, lang, "A", tzone);
+						res = ast_say_date_with_format_zh(chan, t, ints, lang, "A", tzone);
 					} else {
-						res = ast_say_date_with_format_tw(chan, t, ints, lang, "YBdA", tzone);
+						res = ast_say_date_with_format_zh(chan, t, ints, lang, "YBdA", tzone);
 					}
 				}
 				break;
 			case 'R':
-				res = ast_say_date_with_format_tw(chan, t, ints, lang, "kM", tzone);
+				res = ast_say_date_with_format_zh(chan, t, ints, lang, "kM", tzone);
 				break;
 			case 'S':
 				/* Seconds */
@@ -5990,7 +5990,7 @@
 				}
 				break;
 			case 'T':
-				res = ast_say_date_with_format_tw(chan, t, ints, lang, "HMS", tzone);
+				res = ast_say_date_with_format_zh(chan, t, ints, lang, "HMS", tzone);
 				break;
 			case ' ':
 			case '	':
@@ -6024,9 +6024,8 @@
 		return(ast_say_time_pt(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "pt_BR") ) {	/* Brazilian Portuguese syntax */
 		return(ast_say_time_pt_BR(chan, t, ints, lang));
-	} else if (!strcasecmp(lang, "tw") ) {	/* Taiwanese syntax */
-	} else if (!strcasecmp(lang, "tw") || !strcasecmp(lang, "zh") ) {	/* Taiwanese / Chinese syntax */
-		return(ast_say_time_tw(chan, t, ints, lang));
+	} else if (!strncasecmp(lang, "zh", 2) ) {	/* Taiwanese / Chinese syntax */
+		return(ast_say_time_zh(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "gr") ) {  			/* Greek syntax */
 		return(ast_say_time_gr(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "th") ) {
@@ -6250,7 +6249,7 @@
 }
 
 /* Taiwanese / Chinese  syntax */
-int ast_say_time_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang)
+int ast_say_time_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang)
 {
 	struct timeval when = { t, 0 };
 	struct ast_tm tm;
@@ -6342,8 +6341,8 @@
 		return(ast_say_datetime_pt(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "pt_BR") ) {	/* Brazilian Portuguese syntax */
 		return(ast_say_datetime_pt_BR(chan, t, ints, lang));
-	} else if (!strcasecmp(lang, "tw") || !strcasecmp(lang, "zh") ) {	/* Taiwanese / Chinese syntax */
-		return(ast_say_datetime_tw(chan, t, ints, lang));
+	} else if (!strncasecmp(lang, "zh", 2) ) {	/* Taiwanese / Chinese syntax */
+		return(ast_say_datetime_zh(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "gr") ) {  			/* Greek syntax */
 		return(ast_say_datetime_gr(chan, t, ints, lang));
 	} else if (!strcasecmp(lang, "th") ) {	/* Thai syntax */
@@ -6639,7 +6638,7 @@
 }
 
 /* Taiwanese / Chinese syntax */
-int ast_say_datetime_tw(struct ast_channel *chan, time_t t, const char *ints, const char *lang)
+int ast_say_datetime_zh(struct ast_channel *chan, time_t t, const char *ints, const char *lang)
 {
 	struct timeval when = { t, 0 };
 	struct ast_tm tm;