diff --git a/xos/xos_client/xosapi/convenience/voltserviceinstance.py b/xos/xos_client/xosapi/convenience/voltserviceinstance.py
index 47b11bd..5bc11bb 100644
--- a/xos/xos_client/xosapi/convenience/voltserviceinstance.py
+++ b/xos/xos_client/xosapi/convenience/voltserviceinstance.py
@@ -53,8 +53,9 @@
         if not self.subscriber:
             raise Exception("vOLT %s has no subscriber" % self.name)
 
-        olt_device = self.stub.VOLTDevice.objects.get(device_id = self.subscriber.olt_device)
-        olt_port = self.stub.VOLTDevicePort.objects.get(port_id = self.subscriber.olt_port, volt_device_id=olt_device.id)
+        olt_device = self.stub.VOLTDevice.objects.get(name = self.subscriber.olt_device)
+        olt_port = self.stub.VOLTDevicePort.objects.get(name = self.subscriber.olt_port, volt_device_id=olt_device.id)
+
         if olt_port:
             return olt_port.s_tag
         return None