diff --git a/api/abstract_olt_api.proto b/api/abstract_olt_api.proto
index 2dfeff0..cf6e378 100644
--- a/api/abstract_olt_api.proto
+++ b/api/abstract_olt_api.proto
@@ -69,6 +69,7 @@
    string SlotDeviceID=2;
    int32 PortNumber=3;
    int32 OntNumber=4;
+   string SerialNumber=5;
 }
 message AddOntReturn{
    bool Success=1;