diff --git a/common_src/lib/liblynq-sim/include/lynq_sim.h b/common_src/lib/liblynq-sim/include/lynq_sim.h
index c2d7793..ac00626 100755
--- a/common_src/lib/liblynq-sim/include/lynq_sim.h
+++ b/common_src/lib/liblynq-sim/include/lynq_sim.h
@@ -84,6 +84,14 @@
  * 
  */
 int lynq_factory_radio_state(int num);
+/**
+ * @brief set default sim card
+ * @param slot: type [IN] <slot> sim card slot
+ * @return int
+ * 0:success
+ * other:fail
+ */
+int lynq_set_default_sim(const int slot);
 
 
 #ifdef __cplusplus