diff --git a/fetapdtest.py b/fetapdtest.py
index 101cacb..19808c8 100644
--- a/fetapdtest.py
+++ b/fetapdtest.py
@@ -7,10 +7,12 @@ from tuitest import FeApPinConfiguration, FeApUserInterface
 class IllegalEventError(Exception):
 	pass
 
+
+"""
+An abstract state, needed to define all possible events.
+
+"""
 class AbstractState(object):
-	def __init__(self, controller):
-		self._controller = controller
-	
 	def on_registration_in_progress(self):
 		raise IllegalEventError()
 
@@ -46,8 +48,39 @@ class AbstractState(object):
 	
 	def on_timeout(self):
 		raise IllegalEventError()
-		
-class InitState(AbstractState):
+
+
+"""
+The basic state that every other state inherits from. It defines default
+behaviour for some events (overriden if necessary).
+
+"""
+class BaseState(AbstractState):
+	def __init__(self, controller):
+		self._controller = controller
+
+	def on_gabelschalter_up(self):
+		return None
+
+	def on_gabelschalter_down(self):
+		return None
+
+	def on_incoming_call(self):
+		self._controller.get_phone().decline_call()
+
+	def on_call_ended(self):
+		# When an incoming call is declined, a call_ended event occurs, which
+		# needs to be ignored, here.
+		return None
+
+	def on_nummernschalter_active(self):
+		return None
+
+	def on_nummernschalter_input(self, num):
+		return None
+
+
+class InitState(BaseState):
 	def __init__(self, controller):
 		super(InitState, self).__init__(controller)
 		self._controller.get_feap().set_schauzeichen(True)
@@ -56,7 +89,7 @@ class InitState(AbstractState):
 		print('registration in progress')
 		return RegisteringState
 
-class RegisteringState(AbstractState):
+class RegisteringState(BaseState):
 	def __init__(self, controller):
 		super(RegisteringState, self).__init__(controller)
 
@@ -65,7 +98,7 @@ class RegisteringState(AbstractState):
 		self._controller.get_feap().set_schauzeichen(False)
 		return IdleState
 
-class IdleState(AbstractState):
+class IdleState(BaseState):
 	def on_incoming_call(self):
 		print('incomfing call')
 		return SchelltState
@@ -74,16 +107,7 @@ class IdleState(AbstractState):
 		print('gabel up')
 		return DialingState
 	
-	def on_gabelschalter_down(self):
-		pass
-
-	def on_nummernschalter_active(self, x):
-		pass
-
-	def on_nummernschalter_input(self, x):
-		pass
-
-class SchelltState(AbstractState):
+class SchelltState(BaseState):
 	def __init__(self, controller):
 		super(SchelltState, self).__init__(controller)
 		self._controller.get_feap().set_wecker(True)
@@ -99,7 +123,7 @@ class SchelltState(AbstractState):
 		self.__on_leave()
 		return IdleState
 
-class AcceptingState(AbstractState):
+class AcceptingState(BaseState):
 	def __init__(self, controller):
 		super(AcceptingState, self).__init__(controller)
 		self._controller.get_phone().accept_call()
@@ -107,7 +131,7 @@ class AcceptingState(AbstractState):
 	def on_call_accepted(self):
 		return CallRunningState
 
-class CallTerminatingState(AbstractState):
+class CallTerminatingState(BaseState):
 	def __init__(self, controller):
 		super(CallTerminatingState, self).__init__(controller)
 		self._controller.get_phone().end_call()
@@ -118,11 +142,11 @@ class CallTerminatingState(AbstractState):
 	def on_call_accepted(self):
 		return None
 
-class ForgottenState(AbstractState):
+class ForgottenState(BaseState):
 	def on_gabelschalter_down(self):
 		return IdleState
 
-class BusyBeepingState(AbstractState):
+class BusyBeepingState(BaseState):
 	def __init__(self, controller):
 		super(BusyBeepingState, self).__init__(controller)
 		self._controller.get_phone().play_busy_tone()
@@ -137,14 +161,14 @@ class BusyBeepingState(AbstractState):
 		self.__on_leave()
 		return IdleState
 
-class CallRunningState(AbstractState):
+class CallRunningState(BaseState):
 	def on_gabelschalter_down(self):
 		return CallTerminatingState
 	
 	def on_call_ended(self):
 		return BusyBeepingState
 
-class WecktState(AbstractState):
+class WecktState(BaseState):
 	def on_gabelschalter_down(self):
 		return CallTerminatingState
 	
@@ -154,7 +178,7 @@ class WecktState(AbstractState):
 	def on_call_accepted(self):
 		return CallRunningState
 
-class ConnectingState(AbstractState):
+class ConnectingState(BaseState):
 	def on_gabelschalter_down(self):
 		return CallTerminatingState
 	
@@ -171,7 +195,7 @@ class ConnectingState(AbstractState):
 	def on_call_ended(self):
 		return BusyBeepingState
 
-class DialingState(AbstractState):
+class DialingState(BaseState):
 	def __init__(self, controller):
 		super(DialingState, self).__init__(controller)
 		self._controller.get_phone().play_dial_tone()
@@ -206,8 +230,6 @@ class DialingState(AbstractState):
 		self._controller.get_phone().call(self.__number)
 		return ConnectingState
 
-	def on_incoming_call(self):
-		self._controller.get_phone().decline_call()
 
 class StateMachineController(object):
 	def __init__(self, phone, feap):