diff --git a/phoneinterface.py b/phoneinterface.py
index ec0204c..de826a2 100644
--- a/phoneinterface.py
+++ b/phoneinterface.py
@@ -56,6 +56,7 @@ class PhoneInterface(object):
         self.__core.onLinphoneCallOutgoingRinging = self.on_LinphoneCallOutgoingRinging
         self.__core.onLinphoneCallConnected = self.on_LinphoneCallConnected
         self.__core.onLinphoneCallEnd = self.on_LinphoneCallEnd
+        self.__core.onLinphoneCallError = self.on_LinphoneCallError
 
         # Create and add all proxy configs
         for p in config.proxies:
@@ -99,6 +100,10 @@ class PhoneInterface(object):
     def on_LinphoneCallEnd(self, event):
         self.run_callbacks(PhoneEvent.CallEnded)
 
+    def on_LinphoneCallError(self, event):
+        # TODO: Distinguish between different errors
+        self.run_callbacks(PhoneEvent.CallBusy)
+
     def __pollthread(self):
         while self.__running:
             self.__core.process_event()