diff --git a/ndn.cxx/detail/pending-interests-container.h b/ndn.cxx/detail/pending-interests-container.h
index 4d96ed4..78ab10d 100644
--- a/ndn.cxx/detail/pending-interests-container.h
+++ b/ndn.cxx/detail/pending-interests-container.h
@@ -24,19 +24,19 @@
   PendingInterestEntry (Ptr<const Interest> interest)
     : m_interest (interest)
   { }
-  
+
   void
   AddCallbacks (ApiFace::DataCallback onData, ApiFace::TimeoutCallback onTimeout)
   { 
-    m_dataCallback = onData;
-    m_timeoutCallback = onTimeout;
+    m_dataCallbacks.push_back (onData);
+    m_timeoutCallbacks.push_back (onTimeout);
   }
 
   void
   ClearCallbacks ()
   {
-    m_dataCallback = ApiFace::DataCallback ();
-    m_timeoutCallback = ApiFace::TimeoutCallback ();
+    m_dataCallbacks.clear ();
+    m_timeoutCallbacks.clear ();
   }
 
   Ptr<const Interest>
@@ -44,10 +44,32 @@
   {
     return m_interest;
   }
+
+  void
+  ProcessOnData (Ptr<const Interest> interest, Ptr<const Data> data)
+  {
+    for (std::list<ApiFace::DataCallback>::iterator i = m_dataCallbacks.begin ();
+         i != m_dataCallbacks.end ();
+         i++)
+      {
+        (*i) (interest, data);
+      }
+  }
+
+  void
+  ProcessOnTimeout (Ptr<const Interest> interest)
+  {
+    for (std::list<ApiFace::TimeoutCallback>::iterator i = m_timeoutCallbacks.begin ();
+         i != m_timeoutCallbacks.end ();
+         i++)
+      {
+        (*i) (interest);
+      }
+  }
   
-public:
-  ApiFace::DataCallback m_dataCallback;
-  ApiFace::TimeoutCallback m_timeoutCallback;
+private:
+  std::list<ApiFace::DataCallback> m_dataCallbacks;
+  std::list<ApiFace::TimeoutCallback> m_timeoutCallbacks;
   Ptr<const Interest> m_interest;
 };
 
diff --git a/ndn.cxx/detail/timeouts-policy.h b/ndn.cxx/detail/timeouts-policy.h
index 3a52aa2..7d94be1 100644
--- a/ndn.cxx/detail/timeouts-policy.h
+++ b/ndn.cxx/detail/timeouts-policy.h
@@ -147,8 +147,7 @@
       inline void
       ProcessTimeoutEntry (typename parent_trie::iterator item)
       {
-        if (!item->payload ()->m_timeoutCallback.IsNull ())
-          item->payload ()->m_timeoutCallback (item->payload ()->GetInterest ());
+        item->payload ()->ProcessOnTimeout (item->payload ()->GetInterest ());
 
         m_base.erase (item);
       }
diff --git a/ndn.cxx/ndn-api-face.cc b/ndn.cxx/ndn-api-face.cc
index 4be4162..4d522fa 100644
--- a/ndn.cxx/ndn-api-face.cc
+++ b/ndn.cxx/ndn-api-face.cc
@@ -107,6 +107,7 @@
     }
   
   // Record the callback
+  bool needToActuallyExpressInterest = false;
   PendingInterestContainer::iterator entry = m_this->m_pendingInterests.find_exact (interest->GetName ());
   if (entry == m_this->m_pendingInterests.end ())
     {
@@ -114,10 +115,15 @@
         m_this->m_pendingInterests.insert (interest->GetName (), Create <PendingInterestEntry> (interest));
 
       entry = status.first;
+
+      needToActuallyExpressInterest = true;
     }
   entry->payload ()->AddCallbacks (onData, onTimeout);
 
-  ReceiveInterest (interest);
+  if (needToActuallyExpressInterest)
+    {
+      Simulator::ScheduleNow (&Face::ReceiveInterest, this, interest);
+    }
 }
 
 void
@@ -158,12 +164,10 @@
 {
   NS_LOG_INFO (">> D " << data->GetName ());
   
-  ReceiveData (data);
+  Simulator::ScheduleNow (&Face::ReceiveData, this, data);
 }
 
 
-
-
 ///////////////////////////////////////////////
 // private stuff
 
@@ -197,8 +201,7 @@
 {
   // data has been send out from NDN stack towards the application
   NS_LOG_DEBUG ("<< D " << data->GetName ());
-
-  NS_LOG_FUNCTION (this << data);
+  // NS_LOG_FUNCTION (this << data);
 
   if (!IsUp ())
     {
@@ -213,8 +216,7 @@
 
   while (entry != m_this->m_pendingInterests.end ())
     {
-      if (!entry->payload ()->m_dataCallback.IsNull ())
-        entry->payload ()->m_dataCallback (entry->payload ()->GetInterest (), data);
+      entry->payload ()->ProcessOnData (entry->payload ()->GetInterest (), data);
       m_this->m_pendingInterests.erase (entry);
 
       entry = m_this->m_pendingInterests.longest_prefix_match (data->GetName ());