diff --git a/src/org/openlcb/Message.java b/src/org/openlcb/Message.java
index ad1899a7..accb43b4 100644
--- a/src/org/openlcb/Message.java
+++ b/src/org/openlcb/Message.java
@@ -67,5 +67,8 @@ public String toString() {
         return getSourceNodeID().toString()+"                    ";  
      }
 
+     /**
+      * Get the numerical value of the MTI
+      */
      abstract public int getMTI();
 }
diff --git a/src/org/openlcb/MessageDecoder.java b/src/org/openlcb/MessageDecoder.java
index ec4c7a7f..a12cbefa 100644
--- a/src/org/openlcb/MessageDecoder.java
+++ b/src/org/openlcb/MessageDecoder.java
@@ -302,7 +302,7 @@ public void handleTractionProxyReply(TractionProxyReplyMessage msg, Connection s
     }
 
     /**
-     * Handle internal "Unknown MTI" message
+     * Handle internal "Unknown MTI" addressed message
      * @param msg       message to handle
      * @param sender    connection where it came from
      */
@@ -310,4 +310,13 @@ public void handleUnknownMTI(UnknownMtiMessage msg, Connection sender) {
         defaultHandler(msg, sender);
     }
 
+    /**
+     * Handle internal "Unknown MTI" global message
+     * @param msg       message to handle
+     * @param sender    connection where it came from
+     */
+    public void handleUnknownGlobalMTI(UnknownGlobalMtiMessage msg, Connection sender) {
+        defaultHandler(msg, sender);
+    }
+
 }
diff --git a/src/org/openlcb/MessageTypeIdentifier.java b/src/org/openlcb/MessageTypeIdentifier.java
index f3efdbec..d40c3606 100644
--- a/src/org/openlcb/MessageTypeIdentifier.java
+++ b/src/org/openlcb/MessageTypeIdentifier.java
@@ -82,7 +82,8 @@ public enum MessageTypeIdentifier {
         StreamDataProceed           ( true,  false, false, 0, 2,   4, 0, "StreamDataProceed"),
         StreamDataComplete          ( true,  false, false, 0, 2,   5, 0, "StreamDataComplete"),
 
-        UnknownMTI                  ( true,  false, false, 0, 0,   0, 0, "UnknownMTI");                 // invalid external MTI, used internally
+        UnknownMTI                  ( true,  false, false, 0, 0,   0, 0, "UnknownAddressedMTI"),        // invalid external MTI, used internally
+        UnknownGlobalMTI            ( false, false, false, 0, 0,   0, 0, "UnknownGlobalMTI");           // invalid external MTI, used internally
        
         private static java.util.Map<Integer, MessageTypeIdentifier> mapping;
         private static  java.util.Map<Integer, MessageTypeIdentifier> getMap() {
diff --git a/src/org/openlcb/UnknownGlobalMtiMessage.java b/src/org/openlcb/UnknownGlobalMtiMessage.java
new file mode 100644
index 00000000..67b8e179
--- /dev/null
+++ b/src/org/openlcb/UnknownGlobalMtiMessage.java
@@ -0,0 +1,67 @@
+package org.openlcb;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+// For annotations
+import net.jcip.annotations.Immutable;
+import net.jcip.annotations.ThreadSafe; 
+
+/**
+ * Message with unknown/unrecognized/unprocessed MTI
+ * Only relevant for addressed case; unrecognized globals are ignored in proessing.
+ *
+ * @author  Bob Jacobsen   Copyright 2024
+ */
+@Immutable
+@ThreadSafe
+public class UnknownGlobalMtiMessage extends Message {
+    public UnknownGlobalMtiMessage(NodeID source, int originalMTI, byte[] content) {
+        super(source);
+        this.originalMTI = originalMTI;
+    }
+        
+    int originalMTI;
+        
+    public int getOriginalMTI() {
+        return originalMTI;
+    }
+        
+    /**
+     * To be equal, messages have to have the same type and content.
+     */
+    @Override
+    public boolean equals(Object o) {
+        if (o instanceof UnknownGlobalMtiMessage) {
+            return equals((UnknownGlobalMtiMessage) o);
+        }
+        return false;
+    }
+
+    public boolean equals(UnknownGlobalMtiMessage o) {
+        if ((o == null) || (this.originalMTI != o.getOriginalMTI()) ) {
+            return false;
+        }
+        return super.equals(o);
+    }
+    
+    @Override
+    public int getMTI() {
+        return MessageTypeIdentifier.UnknownGlobalMTI.mti();
+    }
+    /**
+     * Implement message-type-specific processing when this message is received by a node.
+     * <p>
+     * Default is to do nothing.
+     */
+    @Override
+    public void applyTo(MessageDecoder decoder, Connection sender) {
+        decoder.handleUnknownGlobalMTI(this, sender);
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder value = new StringBuilder(super.toString());
+        value.append(" Unknown MTI message for MTI 0x");  
+        value.append(Integer.toHexString(getOriginalMTI()&0xFFF).toUpperCase());  
+        return new String(value);   
+    }
+}
diff --git a/src/org/openlcb/can/MessageBuilder.java b/src/org/openlcb/can/MessageBuilder.java
index 531ec75d..bd73948c 100644
--- a/src/org/openlcb/can/MessageBuilder.java
+++ b/src/org/openlcb/can/MessageBuilder.java
@@ -231,7 +231,11 @@ List<Message> processFormat1(CanFrame f) {
             logger.log(Level.SEVERE, "Failed to parse MTI 0x{0}", mtiString);
 
             // return internal-only message
-            retlist.add(new UnknownMtiMessage(source, dest, mti, content ) );
+            if (dest != null) {
+                retlist.add(new UnknownMtiMessage(source, dest, mti, content ) );
+            } else {
+                retlist.add(new UnknownGlobalMtiMessage(source, mti, content ) );
+            }
             return retlist;
         }
 
diff --git a/test/org/openlcb/can/MessageBuilderTest.java b/test/org/openlcb/can/MessageBuilderTest.java
index 3a078e5e..4e3f3521 100644
--- a/test/org/openlcb/can/MessageBuilderTest.java
+++ b/test/org/openlcb/can/MessageBuilderTest.java
@@ -27,6 +27,7 @@
 import org.openlcb.StreamInitiateReplyMessage;
 import org.openlcb.StreamInitiateRequestMessage;
 import org.openlcb.Utilities;
+import org.openlcb.UnknownGlobalMtiMessage;
 import org.openlcb.UnknownMtiMessage;
 import org.openlcb.VerifiedNodeIDNumberMessage;
 import org.openlcb.VerifyNodeIDNumberGlobalMessage;
@@ -797,7 +798,25 @@ public void testOptionalRejectFrame3() {
     }
 
     @Test
-    public void testBogusMti() {
+    public void testBogusAddressedMti() {
+        // should emit "Failed to parse MTI 0x549"
+        OpenLcbCanFrame frame = new OpenLcbCanFrame(0x123);
+        frame.setHeader(0x19549071);
+        frame.setData(new byte[]{0x02, 0x02, (byte)0x12, 0x34});
+
+        MessageBuilder b = new MessageBuilder(map);
+
+        System.err.println("Expect next line to be \"Failed to parse MTI 0x541\"");
+        List<Message> list = b.processFrame(frame);
+
+        // expect that UnknownMTI message will be returned
+        Assert.assertEquals("count", 1, list.size());
+        Message msg = list.get(0);
+        Assert.assertTrue(msg instanceof UnknownMtiMessage);
+    }
+
+    @Test
+    public void testBogusGlobalMti() {
         // should emit "Failed to parse MTI 0x541"
         OpenLcbCanFrame frame = new OpenLcbCanFrame(0x123);
         frame.setHeader(0x19541071);
@@ -811,7 +830,7 @@ public void testBogusMti() {
         // expect that UnknownMTI message will be returned
         Assert.assertEquals("count", 1, list.size());
         Message msg = list.get(0);
-        Assert.assertTrue(msg instanceof UnknownMtiMessage);
+        Assert.assertTrue(msg instanceof UnknownGlobalMtiMessage);
     }
 
     @Test