diff --git a/mitel_ommclient2/session.py b/mitel_ommclient2/session.py
index 78a73b5..c5d0103 100644
--- a/mitel_ommclient2/session.py
+++ b/mitel_ommclient2/session.py
@@ -57,10 +57,13 @@ class Session:
 
             self._connection.connect()
 
+            # Login
             self._connection.send(messages.Open(self.username, self.password))
 
             res = self._wait_for_respose()
 
+            res.raise_on_error()
+
     def request(self, request):
         """
             Sends a request and waits for response