diff --git a/backend/config/constants.js b/backend/config/constants.js
index 0fe470f..6674956 100644
--- a/backend/config/constants.js
+++ b/backend/config/constants.js
@@ -26,6 +26,11 @@ constants.HTTPResultCodes = {
 
 constants.SKILL_ID_LENGTH = 24;
 
+constants.voiceResponseStrings = {
+    QUESTION_NOT_FOUND : 'Sorry, I didnt understan',
+    GENERIC_CONTINUE : 'Would you like to continue'
+}
+
 
 
 module.exports = constants;
\ No newline at end of file
diff --git a/backend/models/alexa.js b/backend/models/alexa.js
index ad58067..d95c855 100644
--- a/backend/models/alexa.js
+++ b/backend/models/alexa.js
@@ -1,6 +1,7 @@
 var Alexa = require ('alexa-sdk');
 const config = require ('../config/config');
 var databaseHelper = require ('../helpers/database');
+const constants = require ('../config/constants');
 
 var handlers = {};
 
@@ -24,31 +25,47 @@ module.exports = {
     alexa.execute ();
   },
   updateModel: function () {
-    //TODO : Alexa-sdk has handlers like SessionEndedRequest, Unhandled ,... that can be used
-
     //Get info from database, and store it for faster response on intent
     databaseHelper
       .getSkill (config.SKILL_DB_ID)
       .then (activeSkill => {
         handlers = {};
+
+        //Handler for launch request
         handlers = {
           LaunchRequest: function () {
             this.response
               .speak (activeSkill.invocationAnswer)
-              .listen (' Would you like to continue ?');
+              .listen (constants.voiceResponseStrings.GENERIC_CONTINUE); //Phrase from listen doesn't work !!!
             //TODO : Maybe to ask user does he want to hear possible intents
             //For this functionality, we need explanation text for each intent (Question)
             this.emit (':responseReady');
           },
         };
+
+        //Handlers for user defined questions
         activeSkill.intents.map (intent => {
           handlers[intent.intentName] = function () {
             this.response
               .speak (intent.answer)
-              .listen ('Would you like to continue ?');
+              .listen (constants.voiceResponseStrings.GENERIC_CONTINUE); //Phrase from listen doesn't work !!!
             this.emit (':responseReady');
           };
         });
+
+        //Default handlers for unknown questions and session close
+
+        handlers.Unhandled = function () {
+          this.response
+            .speak (constants.voiceResponseStrings.QUESTION_NOT_FOUND)
+            .listen (constants.voiceResponseStrings.GENERIC_CONTINUE);
+        }
+
+        handlers.SessionEndedRequest = function(){
+          //We don't care for now
+        }
+
+
       })
       .catch (e => {
         //Something is wrong, skill is not ready, use catch-all intent to inform user