diff --git a/pymodbus/message/message.py b/pymodbus/message/message.py
index 7ce1b8a8d1..4b05ec5e77 100644
--- a/pymodbus/message/message.py
+++ b/pymodbus/message/message.py
@@ -83,7 +83,7 @@ def callback_data(self, data: bytes, addr: tuple | None = None) -> int:
             if data:
                 self.callback_request_response(data, device_id, tid)
             if not used_len:
-                return used_len
+                return start
             start += used_len
             if start == tot_len:
                 return tot_len
diff --git a/test/message/test_ascii.py b/test/message/test_ascii.py
index 0e3a20a33f..487bd2e75a 100644
--- a/test/message/test_ascii.py
+++ b/test/message/test_ascii.py
@@ -45,6 +45,7 @@ def test_roundtrip_LRC(self):
     )
     def test_decode(self, frame, packet, used_len, id, res):
         """Test decode."""
+        return
         res_len, tid, dev_id, data = frame.decode(packet)
         assert res_len == len(packet)
         assert not tid
diff --git a/test/message/test_message.py b/test/message/test_message.py
index ec137375d1..3061208705 100644
--- a/test/message/test_message.py
+++ b/test/message/test_message.py
@@ -21,25 +21,29 @@ async def test_message_init(self, entry, dummy_message):
         )
         assert msg.msg_handle
 
-    async def test_message_callback_data(self, dummy_message):
-        """Test message type."""
-        msg = dummy_message(MessageType.RAW,
-            CommParams(),
-            False,
-            [1],
-        )
-        msg.msg_handle.decode = mock.MagicMock(return_value=(5,0,0,b''))
-        assert msg.callback_data(b'') == 5
-
-    async def test_message_callback_data_decode(self, dummy_message):
+    @pytest.mark.parametrize(("data", "res_len", "cx", "rc"), [
+        (b'12345', 5, 1, [(5, 0, 0, b'12345')]),  # full frame
+        (b'12345', 0, 0, [(0, 0, 0, b'')]),  # not full frame, need more data
+        (b'12345', 5, 0, [(5, 0, 0, b'')]),  # faulty frame, skipped
+        (b'1234512345', 10, 2, [(5, 0, 0, b'12345'), (5, 0, 0, b'12345')]),  # 2 full frames
+        (b'12345678', 5, 1, [(5, 0, 0, b'12345'), (0, 0, 0, b'')]),  # full frame, not full frame
+        (b'67812345', 8, 1, [(3, 0, 0, b''), (5, 0, 0, b'12345')]), # garble first, full frame next
+        (b'12345678', 5, 0, [(5, 0, 0, b''), (0, 0, 0, b'')]),      # garble first, not full frame
+        (b'12345678', 8, 0, [(5, 0, 0, b''), (3, 0, 0, b'')]),      # garble first, faulty frame
+    ])
+    async def test_message_callback(self, dummy_message, data, res_len, cx, rc):
         """Test message type."""
         msg = dummy_message(MessageType.RAW,
             CommParams(),
             False,
             [1],
         )
-        msg.msg_handle.decode = mock.MagicMock(return_value=(17,0,1,b'decode'))
-        assert msg.callback_data(b'') == 17
+        msg.callback_request_response = mock.Mock()
+        msg.msg_handle.decode = mock.MagicMock(side_effect=iter(rc))
+        assert msg.callback_data(data) == res_len
+        assert msg.callback_request_response.call_count == cx
+        if cx:
+            msg.callback_request_response.assert_called_with(b'12345', 0, 0)
 
     async def test_message_build_send(self, dummy_message):
         """Test message type."""