diff --git a/src/net/java/sip/communicator/service/protocol/media/TransportManager.java b/src/net/java/sip/communicator/service/protocol/media/TransportManager.java
index 419a0011f..ae9a6d31c 100644
--- a/src/net/java/sip/communicator/service/protocol/media/TransportManager.java
+++ b/src/net/java/sip/communicator/service/protocol/media/TransportManager.java
@@ -42,7 +42,8 @@ public abstract class TransportManager<U extends MediaAwareCallPeer<?, ?, ?>>
      * Initialized by {@link #initializePortNumbers()}.
      * </p>
      */
-    private static PortTracker defaultPortTracker = new PortTracker(5000, 6000);
+    private static final PortTracker defaultPortTracker
+        = new PortTracker(5000, 6000);
 
     /**
      * The port tracker that we should use when binding video media streams.
@@ -51,25 +52,25 @@ public abstract class TransportManager<U extends MediaAwareCallPeer<?, ?, ?>>
      * necessary properties are set.
      * </p>
      */
-    private static PortTracker videoPortTracker = null;
+    private static PortTracker videoPortTracker;
 
     /**
      * The port tracker that we should use when binding data channels.
      * <p>
      * Potentially initialized by {@link #initializePortNumbers()} if the
-     * necessary properties are set
+     * necessary properties are set.
      * </p>
      */
-    private static PortTracker dataChannelPortTracker = null;
+    private static PortTracker dataPortTracker;
 
     /**
      * The port tracker that we should use when binding data media streams.
      * <p>
      * Potentially initialized by {@link #initializePortNumbers()} if the
-     * necessary properties are set
+     * necessary properties are set.
      * </p>
      */
-    private static PortTracker audioPortTracker = null;
+    private static PortTracker audioPortTracker;
 
     /**
      * RTP audio DSCP configuration property name.
@@ -281,70 +282,72 @@ protected StreamConnector createStreamConnector(MediaType mediaType)
     }
 
     /**
-     * (Re)Sets the all the port allocators to reflect current values specified
-     * in the <tt>ConfigurationService</tt>. Calling this method may very well
-     * result in creating new port allocators or destroying existing ones.
+     * Tries to set the ranges of the <tt>PortTracker</tt>s (e.g. default,
+     * audio, video, data channel) to the values specified in the
+     * <tt>ConfigurationService</tt>.
      */
-    protected static void initializePortNumbers()
+    protected synchronized static void initializePortNumbers()
     {
         //try the default tracker first
         ConfigurationService cfg
             = ProtocolMediaActivator.getConfigurationService();
-        String minPortNumberStr
+        String minPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MIN_MEDIA_PORT_NUMBER_PROPERTY_NAME);
-        String maxPortNumberStr
+        String maxPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MAX_MEDIA_PORT_NUMBER_PROPERTY_NAME);
 
-        //try to send the specified range. If there's no specified range in
-        //configuration, we'll just leave the tracker as it is: [5000 to 6000]
-        defaultPortTracker.tryRange(minPortNumberStr, maxPortNumberStr);
+        //Try the specified range; otherwise, leave the tracker as it is:
+        //[5000, 6000].
+        defaultPortTracker.tryRange(minPort, maxPort);
 
         //try the VIDEO tracker
-        minPortNumberStr
+        minPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MIN_VIDEO_PORT_NUMBER_PROPERTY_NAME);
-        maxPortNumberStr
+        maxPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MAX_VIDEO_PORT_NUMBER_PROPERTY_NAME);
-        //try to send the specified range. If there's no specified range in
-        //configuration, we'll just leave this tracker to null
-        videoPortTracker
-            = PortTracker.createTracker(minPortNumberStr, maxPortNumberStr);
+        //Try the specified range; otherwise, leave the tracker to null.
+        if (videoPortTracker == null)
+            videoPortTracker = PortTracker.createTracker(minPort, maxPort);
+        else
+            videoPortTracker.tryRange(minPort, maxPort);
 
         //try the AUDIO tracker
-        minPortNumberStr
+        minPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MIN_AUDIO_PORT_NUMBER_PROPERTY_NAME);
-        maxPortNumberStr
+        maxPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MAX_AUDIO_PORT_NUMBER_PROPERTY_NAME);
-        //try to send the specified range. If there's no specified range in
-        //configuration, we'll just leave this tracker to null
-        audioPortTracker
-            = PortTracker.createTracker(minPortNumberStr, maxPortNumberStr);
+        //Try the specified range; otherwise, leave the tracker to null.
+        if (audioPortTracker == null)
+            audioPortTracker = PortTracker.createTracker(minPort, maxPort);
+        else
+            audioPortTracker.tryRange(minPort, maxPort);
 
         //try the DATA CHANNEL tracker
-        minPortNumberStr
+        minPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MIN_DATA_CHANNEL_PORT_NUMBER_PROPERTY_NAME);
-        maxPortNumberStr
+        maxPort
             = cfg.getString(
                     OperationSetBasicTelephony
                         .MAX_DATA_CHANNEL_PORT_NUMBER_PROPERTY_NAME);
-
-        //try to send the specified range. If there's no specified range in
-        //configuration, we'll just leave this tracker to null
-        dataChannelPortTracker
-            = PortTracker.createTracker(minPortNumberStr, maxPortNumberStr);
+        //Try the specified range; otherwise, leave the tracker to null.
+        if (dataPortTracker == null)
+            dataPortTracker = PortTracker.createTracker(minPort, maxPort);
+        else
+            dataPortTracker.tryRange(minPort, maxPort);
     }
 
     /**
@@ -594,11 +597,13 @@ protected static PortTracker getPortTracker(MediaType mediaType)
         case AUDIO:
             if (audioPortTracker != null)
                 return audioPortTracker;
-            break;
+            else
+                break;
         case VIDEO:
             if (videoPortTracker != null)
                 return videoPortTracker;
-            break;
+            else
+                break;
         }
 
         return defaultPortTracker;