Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 166508)
+++ channels/chan_sip.c	(working copy)
@@ -22008,7 +22008,7 @@
 	int no = 0;
 	int ok = FALSE;
 	char varbuf[30];
-	char *inbuf = data;
+	char *inbuf = data, *subbuf;
 	
 	if (ast_strlen_zero(inbuf)) {
 		ast_log(LOG_WARNING, "This application requires the argument: Header\n");
@@ -22022,13 +22022,18 @@
 		snprintf(varbuf, sizeof(varbuf), "__SIPADDHEADER%.2d", no);
 
 		/* Compare without the leading underscores */
-		if( (pbx_builtin_getvar_helper(chan, (const char *) varbuf + 2) == (const char *) NULL) )
+		if ((pbx_builtin_getvar_helper(chan, (const char *) varbuf + 2) == (const char *) NULL)) {
 			ok = TRUE;
+		}
 	}
 	if (ok) {
-		pbx_builtin_setvar_helper (chan, varbuf, inbuf);
-		if (sipdebug)
+		size_t len = strlen(inbuf);
+		subbuf = alloca(len + 1);
+		ast_get_encoded_str(inbuf, subbuf, len + 1);
+		pbx_builtin_setvar_helper(chan, varbuf, subbuf);
+		if (sipdebug) {
 			ast_debug(1, "SIP Header added \"%s\" as %s\n", inbuf, varbuf);
+		}
 	} else {
 		ast_log(LOG_WARNING, "Too many SIP headers added, max 50\n");
 	}
Index: include/asterisk/app.h
===================================================================
--- include/asterisk/app.h	(revision 166508)
+++ include/asterisk/app.h	(working copy)
@@ -480,6 +480,9 @@
 /*! \brief Decode an encoded control or extended ASCII character */
 int ast_get_encoded_char(const char *stream, char *result, size_t *consumed);
 
+/*! \brief Decode a string which may contain multiple encoded control or extended ASCII characters */
+int ast_get_encoded_str(const char *stream, char *result, size_t result_size);
+
 #if defined(__cplusplus) || defined(c_plusplus)
 }
 #endif
Index: main/app.c
===================================================================
--- main/app.c	(revision 166508)
+++ main/app.c	(working copy)
@@ -1775,3 +1775,16 @@
 	return 0;
 }
 
+int ast_get_encoded_str(const char *stream, char *result, size_t result_size)
+{
+	char *cur = result;
+	size_t consumed;
+
+	while (cur < result + result_size - 1 && !ast_get_encoded_char(stream, cur, &consumed)) {
+		cur++;
+		stream += consumed;
+	}
+	*cur = '\0';
+	return 0;
+}
+