diff --git a/callattendant/app.py b/callattendant/app.py
index 6455955..940ce33 100755
--- a/callattendant/app.py
+++ b/callattendant/app.py
@@ -27,6 +27,7 @@
 import queue
 import sqlite3
 import time
+import threading
 from pprint import pprint
 from shutil import copyfile
 
@@ -51,6 +52,9 @@ def __init__(self, config):
         # The application-wide configuration
         self.config = config
 
+        # Thread synchonization object
+        self._stop_event = threading.Event()
+
         # Open the database
         if self.config["TESTING"]:
             self.db = sqlite3.connect(":memory:")
@@ -99,10 +103,11 @@ def handle_caller(self, caller):
             pprint(caller)
         self._caller_queue.put(caller)
 
-    def process_calls(self):
+    def run(self):
         """
         Processes incoming callers by logging, screening, blocking
         and/or recording messages.
+            :returns: exit code 1 on error otherwise 0
         """
         # Get relevant config settings
         screening_mode = self.config['SCREENING_MODE']
@@ -114,18 +119,23 @@ def process_calls(self):
         permitted_greeting_file = permitted['greeting_file']
 
         # Instruct the modem to start feeding calls into the caller queue
-        self.modem.handle_calls(self.handle_caller)
+        self.modem.start(self.handle_caller)
 
         # If testing, allow queue to be filled before processing for clean, readable logs
         if self.config["TESTING"]:
             time.sleep(1)
 
         # Process incoming calls
-        while 1:
+        exit_code = 0
+        caller = {}
+        print("Waiting for call...")
+        while not self._stop_event.is_set():
             try:
                 # Wait (blocking) for a caller
-                print("Waiting for call...")
-                caller = self._caller_queue.get()
+                try:
+                    caller = self._caller_queue.get(True, 3.0)
+                except queue.Empty:
+                    continue
 
                 # An incoming call has occurred, log it
                 number = caller["NMBR"]
@@ -198,10 +208,27 @@ def process_calls(self):
                 if ok_to_answer and len(actions) > 0:
                     self.answer_call(actions, greeting, call_no, caller)
 
+                print("Waiting for next call...")
+
+            except KeyboardInterrupt:
+                print("** User initiated shutdown")
+                self._stop_event.set()
             except Exception as e:
                 pprint(e)
-                print("** Error running callattendant. Exiting.")
-                return 1
+                print("** Error running callattendant")
+                self._stop_event.set()
+                exit_code = 1
+        return exit_code
+
+    def shutdown(self):
+        print("Shutting down...")
+        print("-> Stopping modem")
+        self.modem.stop()
+        print("-> Stopping voice mail")
+        self.voice_mail.stop()
+        print("-> Releasing resources")
+        self.approved_indicator.close()
+        self.blocked_indicator.close()
 
     def answer_call(self, actions, greeting, call_no, caller):
         """
@@ -389,8 +416,12 @@ def main(argv):
 
     # Create and start the application
     app = CallAttendant(config)
-    app.process_calls()
-    return 0
+    exit_code = 0
+    try:
+        exit_code = app.run()
+    finally:
+        app.shutdown()
+    return exit_code
 
 
 if __name__ == '__main__':
diff --git a/callattendant/hardware/modem.py b/callattendant/hardware/modem.py
index ae78653..f9d2fbe 100644
--- a/callattendant/hardware/modem.py
+++ b/callattendant/hardware/modem.py
@@ -139,8 +139,10 @@ def __init__(self, config):
         self.config = config
         self.model = None
 
-        # Thread synchronization object
+        # Thread synchronization objects
+        self._stop_event = threading.Event()
         self._lock = threading.RLock()
+        self._thread = None
 
         # Ring notifications
         self.ring_indicator = RingIndicator(
@@ -152,7 +154,9 @@ def __init__(self, config):
         self._serial = serial.Serial()
 
     def open_serial_port(self):
-        """Detects and opens the serial port attached to the modem."""
+        """
+        Detects and opens the serial port attached to the modem.
+        """
         # List all the Serial COM Ports on Raspberry Pi
         proc = subprocess.Popen(['ls /dev/tty[A-Za-z]*'], shell=True, stdout=subprocess.PIPE)
         com_ports = proc.communicate()[0]
@@ -186,18 +190,20 @@ def open_serial_port(self):
         return False
 
     def close_serial_port(self):
-        """Closes the serial port attached to the modem."""
-        print("Closing Serial Port")
+        """
+        Closes the serial port attached to the modem.
+        """
+        print("-> Closing Serial Port")
         try:
             if self._serial.isOpen():
                 self._serial.close()
-                print("Serial Port closed...")
+                print("-> Serial Port closed")
         except Exception as e:
             print(e)
             print("Error: Unable to close the Serial Port.")
             sys.exit()
 
-    def handle_calls(self, handle_caller):
+    def start(self, handle_caller):
         """
         Starts the thread that processes incoming data.
             :param handle_caller:
@@ -205,11 +211,20 @@ def handle_calls(self, handle_caller):
         """
         self._init_modem()
 
-        self.event_thread = threading.Thread(
+        self._thread = threading.Thread(
             target=self._call_handler,
             kwargs={'handle_caller': handle_caller})
-        self.event_thread.name = "modem_call_handler"
-        self.event_thread.start()
+        self._thread.name = "modem_call_handler"
+        self._thread.start()
+
+    def stop(self):
+        """
+        Stops the modem thread and releases hardware resources.
+        """
+        self._stop_event.set()
+        if self._thread:
+            self._thread.join()
+        self.ring_indicator.close()
 
     def _call_handler(self, handle_caller):
         """
@@ -242,7 +257,7 @@ def _call_handler(self, handle_caller):
             # This loop reads incoming data from the serial port and
             # posts the caller data to the handle_caller function
             call_record = {}
-            while 1:
+            while not self._stop_event.is_set():
                 modem_data = b''
 
                 # Read from the modem
@@ -308,7 +323,7 @@ def _call_handler(self, handle_caller):
 
         finally:
             if dev_mode:
-                print("Closing modem log file")
+                print("-> Closing modem log file")
                 logfile.close()
 
     def pick_up(self):
diff --git a/callattendant/messaging/voicemail.py b/callattendant/messaging/voicemail.py
index 1c96020..a99e6ab 100644
--- a/callattendant/messaging/voicemail.py
+++ b/callattendant/messaging/voicemail.py
@@ -60,9 +60,10 @@ def __init__(self, db, config, modem):
         self.messages = Message(db, config)
 
         # Start the thread that monitors the message events and updates the indicators
-        self.event_thread = threading.Thread(target=self._event_handler)
-        self.event_thread.name = "voice_mail_event_handler"
-        self.event_thread.start()
+        self._stop_event = threading.Event()
+        self._thread = threading.Thread(target=self._event_handler)
+        self._thread.name = "voice_mail_event_handler"
+        self._thread.start()
 
         # Pulse the indicator if an unplayed msg is waiting
         self.reset_message_indicator()
@@ -70,13 +71,22 @@ def __init__(self, db, config, modem):
         if self.config["DEBUG"]:
             print("VoiceMail initialized")
 
+    def stop(self):
+        """
+        Stops the voice mail thread and releases hardware resources.
+        """
+        self._stop_event.set()
+        self._thread.join()
+        self.message_indicator.close()
+        self.message_count_indicator.close()
+
     def _event_handler(self):
         """
         Thread function that updates the message indicators upon a message event.
         """
-        while 1:
+        while not self._stop_event.is_set():
             # Get the number of unread messages
-            if self.message_event.wait():
+            if self.message_event.wait(2.0):
                 if self.config["DEBUG"]:
                     print("Message Event triggered")
                 self.reset_message_indicator()
diff --git a/callattendant/userinterface/webapp.py b/callattendant/userinterface/webapp.py
index 0c49720..1bec2dd 100644
--- a/callattendant/userinterface/webapp.py
+++ b/callattendant/userinterface/webapp.py
@@ -984,7 +984,7 @@ def get_pagination(**kwargs):
 def run_flask(config):
     '''
     Runs the Flask webapp.
-        :param database: full path to the callattendant database file
+        :param config: the application-wide master config object
     '''
     app.secret_key = get_random_string()
     with app.app_context():
@@ -1007,6 +1007,6 @@ def run_flask(config):
 def start(config):
     '''
     Starts the Flask webapp in a separate thread.
-        :param database: full path to the callattendant database file
+        :param config: the application-wide master config object
     '''
     _thread.start_new_thread(run_flask, (config,))
diff --git a/tests/test_modem.py b/tests/test_modem.py
index 0ad1227..43b70ff 100644
--- a/tests/test_modem.py
+++ b/tests/test_modem.py
@@ -60,7 +60,7 @@ def modem():
 
     yield modem
 
-    modem.ring_indicator.close()
+    modem.stop()
 
 
 def test_profile_reset(modem):
diff --git a/tests/test_voicemail.py b/tests/test_voicemail.py
index 0b92232..d5e5ec1 100644
--- a/tests/test_voicemail.py
+++ b/tests/test_voicemail.py
@@ -71,14 +71,15 @@ def modem(db, config):
     modem = Modem(config)
     modem.open_serial_port()
     yield modem
-    modem.ring_indicator.close()
+    modem.stop()
 
 
 @pytest.fixture(scope='module')
 def voicemail(db, config, modem):
 
     voicemail = VoiceMail(db, config, modem)
-    return voicemail
+    yield voicemail
+    voicemail.stop()
 
 
 # Skip the test when running under continous integraion