diff --git a/changelog/3615.fixed.md b/changelog/3615.fixed.md
new file mode 100644
index 000000000..b14dfd70f
--- /dev/null
+++ b/changelog/3615.fixed.md
@@ -0,0 +1 @@
+- Fixed race condition where `RTVIObserver` could send messages before `DailyTransport` join completed. Outbound messages are now queued & delivered after the transport is ready.
diff --git a/src/pipecat/transports/daily/transport.py b/src/pipecat/transports/daily/transport.py
index 5df7bcffd..9575fd51b 100644
--- a/src/pipecat/transports/daily/transport.py
+++ b/src/pipecat/transports/daily/transport.py
@@ -511,6 +511,7 @@ class DailyTransportClient(EventHandler):
         self._event_task = None
         self._audio_task = None
         self._video_task = None
+        self._join_message_queue: list = []
 
         # Input and ouput sample rates. They will be initialize on setup().
         self._in_sample_rate = 0
@@ -577,7 +578,8 @@ class DailyTransportClient(EventHandler):
             error: An error description or None.
         """
         if not self._joined:
-            return "Unable to send messages before joining."
+            self._join_message_queue.append(frame)
+            return None
 
         participant_id = None
         if isinstance(
@@ -778,6 +780,8 @@ class DailyTransportClient(EventHandler):
             await self._callbacks.on_joined(data)
 
             self._joined_event.set()
+
+            await self._flush_join_messages()
         else:
             error_msg = f"Error joining {self._room_url}: {error}"
             logger.error(error_msg)
@@ -1551,6 +1555,12 @@ class DailyTransportClient(EventHandler):
             await callback(*args)
             queue.task_done()
 
+    async def _flush_join_messages(self):
+        """Send any messages that were queued before join completed."""
+        for frame in self._join_message_queue:
+            await self.send_message(frame)
+        self._join_message_queue.clear()
+
     def _get_event_loop(self) -> asyncio.AbstractEventLoop:
         """Get the event loop from the task manager."""
         if not self._task_manager: