diff --git a/coreapi/presence.c b/coreapi/presence.c
index af4c5184d..08996329f 100644
--- a/coreapi/presence.c
+++ b/coreapi/presence.c
@@ -170,7 +170,7 @@ static time_t parse_timestamp(const char *timestamp) {
 	return seconds - timezone;
 }
 
-static char * timestamp_to_string(time_t timestamp) {
+char * linphone_timestamp_to_rfc3339_string(time_t timestamp) {
 	char timestamp_str[22];
 	struct tm *ret;
 #ifndef WIN32
@@ -1604,7 +1604,7 @@ static void write_xml_presence_note_obj(LinphonePresenceNote *note, struct _pres
 
 static int write_xml_presence_timestamp(xmlTextWriterPtr writer, time_t timestamp) {
 	int err;
-	char *timestamp_str = timestamp_to_string(timestamp);
+	char *timestamp_str = linphone_timestamp_to_rfc3339_string(timestamp);
 	err = xmlTextWriterWriteElement(writer, (const xmlChar *)"timestamp", (const xmlChar *)timestamp_str);
 	if (timestamp_str) ms_free(timestamp_str);
 	return err;
diff --git a/coreapi/private.h b/coreapi/private.h
index 45dc5f305..e2feef54a 100644
--- a/coreapi/private.h
+++ b/coreapi/private.h
@@ -854,11 +854,18 @@ char * linphone_get_xml_text_content(xmlparsing_context_t *xml_ctx, const char *
 void linphone_free_xml_text_content(const char *text);
 xmlXPathObjectPtr linphone_get_xml_xpath_object_for_node_list(xmlparsing_context_t *xml_ctx, const char *xpath_expression);
 
+/*****************************************************************************
+ * OTHER UTILITY FUNCTIONS                                                     *
+ ****************************************************************************/
+char * linphone_timestamp_to_rfc3339_string(time_t timestamp);
+
+
 static inline const LinphoneErrorInfo *linphone_error_info_from_sal_op(const SalOp *op){
 	if (op==NULL) return (LinphoneErrorInfo*)sal_error_info_none();
 	return (const LinphoneErrorInfo*)sal_op_get_error_info(op);
 }
 
+
 /** Belle Sip-based objects need unique ids
   */