diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_filetransfer/JingleFileTransferSession.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_filetransfer/JingleFileTransferSession.java
index 83c9c9650..2afa79765 100644
--- a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_filetransfer/JingleFileTransferSession.java
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_filetransfer/JingleFileTransferSession.java
@@ -48,6 +48,7 @@ import org.jivesoftware.smackx.jingle.exception.UnsupportedJingleTransportExcept
 import org.jivesoftware.smackx.jingle_filetransfer.callback.JingleFileTransferCallback;
 import org.jivesoftware.smackx.jingle_filetransfer.element.JingleFileTransferChild;
 import org.jivesoftware.smackx.jingle_filetransfer.element.JingleFileTransferContentDescription;
+import org.jivesoftware.smackx.jingle_ibb.element.JingleIBBTransport;
 import org.jxmpp.jid.FullJid;
 
 /**
@@ -78,6 +79,7 @@ public class JingleFileTransferSession extends AbstractJingleSession {
         this.sessionId = StringUtils.randomString(24);
         this.role = JingleContent.Creator.initiator;
 
+        //Create file content element
         JingleFileTransferChild fileTransferChild = fileElementFromFile(send);
         JingleContent.Builder cb = JingleContent.getBuilder();
         cb.setSenders(JingleContent.Senders.initiator)
@@ -88,7 +90,7 @@ public class JingleFileTransferSession extends AbstractJingleSession {
         try {
             cb.addTransport(defaultTransport());
         } catch (Exception e) {
-            throw new AssertionError("At least IBB should work. " + e);
+            throw new AssertionError("At least IBB should work as a transport method. " + e);
         }
 
         this.proposedContent = cb.build();
@@ -423,7 +425,14 @@ public class JingleFileTransferSession extends AbstractJingleSession {
 
                 @Override
                 public void onSessionFailure(JingleTransportFailureException reason) {
-                    //TODO: Send transport-failed or so.
+                    //TODO: Send transport-replace to fall back to IBB
+                    // Do we already use IBB?
+                    if (transportHandler.getNamespace().equals(JingleIBBTransport.NAMESPACE_V1)) {
+                        //fail
+                    } else {
+                        Jingle.Builder jb = Jingle.getBuilder();
+                        jb.setAction(JingleAction.transport_replace);
+                    }
                 }
             };
 
@@ -436,7 +445,7 @@ public class JingleFileTransferSession extends AbstractJingleSession {
 
                 @Override
                 public void onSessionFailure(JingleTransportFailureException reason) {
-                    //TODO: Send transport failed
+                    LOGGER.log(Level.SEVERE, "SESSION FAILIURE: ", reason);
                 }
             };
 
diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_ibb/JingleIBBTransportHandler.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_ibb/JingleIBBTransportHandler.java
index 37fc7ac84..91ca2bc3e 100644
--- a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_ibb/JingleIBBTransportHandler.java
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_ibb/JingleIBBTransportHandler.java
@@ -90,6 +90,11 @@ public class JingleIBBTransportHandler implements JingleTransportHandler<JingleI
         return jingleSessionHandler.getConnection();
     }
 
+    @Override
+    public String getNamespace() {
+        return JingleIBBTransport.NAMESPACE_V1;
+    }
+
     @Override
     public boolean onTransportInfoReceived(Jingle transportInfo) {
         return false;
diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_s5b/JingleS5BTransportHandler.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_s5b/JingleS5BTransportHandler.java
index 7cfea490d..139b99516 100644
--- a/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_s5b/JingleS5BTransportHandler.java
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_s5b/JingleS5BTransportHandler.java
@@ -37,6 +37,7 @@ import org.jivesoftware.smackx.jingle.element.Jingle;
 import org.jivesoftware.smackx.jingle.element.JingleAction;
 import org.jivesoftware.smackx.jingle.element.JingleContent;
 import org.jivesoftware.smackx.jingle.element.JingleContentTransportCandidate;
+import org.jivesoftware.smackx.jingle.exception.JingleTransportFailureException;
 import org.jivesoftware.smackx.jingle_s5b.elements.JingleS5BTransport;
 import org.jivesoftware.smackx.jingle_s5b.elements.JingleS5BTransportCandidate;
 import org.jivesoftware.smackx.jingle_s5b.elements.JingleS5BTransportInfo;
@@ -109,6 +110,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
                 break;
             }
             catch (TimeoutException | IOException | SmackException | XMPPException | InterruptedException e) {
+                //We cannot connect to transport candidate. Try others...
                 LOGGER.log(Level.WARNING, "Could not connect to " + address + ": " + e, e);
             }
         }
@@ -138,7 +140,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
             try {
                 getConnection().sendStanza(jingle);
             } catch (SmackException.NotConnectedException | InterruptedException e) {
-                LOGGER.log(Level.SEVERE, "Could not send candidate-used transport-info: " + e, e);
+                callback.onSessionFailure(new JingleTransportFailureException(e));
             }
         } else {
             //Candidate error
@@ -168,7 +170,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
             try {
                 getConnection().sendStanza(jingle);
             } catch (SmackException.NotConnectedException | InterruptedException e) {
-                LOGGER.log(Level.SEVERE, "Could not send candidate-error transport-info: " + e, e);
+                callback.onSessionFailure(new JingleTransportFailureException(e));
             }
         }
 
@@ -180,6 +182,11 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
         return sessionHandler.getConnection();
     }
 
+    @Override
+    public String getNamespace() {
+        return JingleS5BTransport.NAMESPACE_V1;
+    }
+
     private interface JingleS5BTransportHandlerInterface {
         boolean onTransportInfoReceived(Jingle transportInfo);
     }
@@ -216,7 +223,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
 
                     if (usedCandidate == null) {
                         //Error unknown candidate.
-
+                        //TODO: Ignore? Not specified in xep-0260
                     } else {
 
                         //We already have a remote candidate selected.
@@ -244,6 +251,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
                             }
                             catch (TimeoutException | IOException | SmackException | XMPPException | InterruptedException e) {
                                 LOGGER.log(Level.WARNING, "Could not connect to own proxy at " + address + ": " + e, e);
+                                callback.onSessionFailure(new JingleTransportFailureException(e));
                             }
                         }
 
@@ -259,13 +267,14 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
                     parent.remoteCandidateError = true;
                     if (parent.localCandidateError) {
                         //Session transport-failed
+                        //TODO: Fallback
                     } else {
                         state = new CandidateUsedReceived(parent);
                     }
                     break;
 
                 case JingleS5BTransportInfo.ProxyError.ELEMENT:
-
+                    //???
                     break;
             }
 
@@ -290,10 +299,16 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
             JingleS5BTransport transport = (JingleS5BTransport) content.getJingleTransports().get(0);
             JingleS5BTransportInfo info = (JingleS5BTransportInfo) transport.getInfos().get(0);
 
-            if (info.getElementName().equals(JingleS5BTransportInfo.CandidateActivated.ELEMENT)) {
-                //TODO: Check if same candidate
-                LOGGER.log(Level.INFO, "Established connection with " + parent.usedCandidate.getHost());
-                callback.onSessionEstablished(new Socks5BytestreamSession(parent.connectedSocket, parent.usedCandidate.getType() == JingleS5BTransportCandidate.Type.direct));
+            if (JingleS5BTransportInfo.CandidateActivated.ELEMENT.equals(info.getElementName())) {
+                JingleS5BTransportInfo.CandidateActivated candidateActivated =
+                        (JingleS5BTransportInfo.CandidateActivated) info;
+
+                if (!parent.usedCandidate.getCandidateId().equals(candidateActivated.getCandidateId())) {
+                    //TODO: Unknown candidate. Not specified in xep-0260?
+                } else {
+                    LOGGER.log(Level.INFO, "Established connection with " + parent.usedCandidate.getHost());
+                    callback.onSessionEstablished(new Socks5BytestreamSession(parent.connectedSocket, parent.usedCandidate.getType() == JingleS5BTransportCandidate.Type.direct));
+                }
                 return true;
             }
             return false;
@@ -315,6 +330,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
                             getConnection().createStanzaCollectorAndSend(activateProxy).nextResultOrThrow();
                         } catch (SmackException.NoResponseException | XMPPException.XMPPErrorException | SmackException.NotConnectedException | InterruptedException e) {
                             LOGGER.log(Level.SEVERE, "Could not activate proxy server: " + e, e);
+                            callback.onSessionFailure(new JingleTransportFailureException(e));
                         }
                     }
 
@@ -347,6 +363,7 @@ public class JingleS5BTransportHandler implements JingleTransportHandler<JingleS
                         getConnection().sendStanza(j);
                     } catch (SmackException.NotConnectedException | InterruptedException e) {
                         LOGGER.log(Level.SEVERE, "Could not send candidate-activated : " + e, e);
+                        callback.onSessionFailure(new JingleTransportFailureException(e));
                     }
 
                     LOGGER.log(Level.INFO, "Established connection with " + parent.usedCandidate.getHost());
diff --git a/smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/JingleTransportHandler.java b/smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/JingleTransportHandler.java
index 4d84166d3..b004c4c9c 100644
--- a/smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/JingleTransportHandler.java
+++ b/smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/JingleTransportHandler.java
@@ -31,4 +31,6 @@ public interface JingleTransportHandler<D extends JingleContentTransport> extend
     void establishIncomingSession(JingleTransportEstablishedCallback callback);
 
     XMPPConnection getConnection();
+
+    String getNamespace();
 }