diff --git a/src/pipecat/pipeline/task.py b/src/pipecat/pipeline/task.py
index 79816a868..0c534a006 100644
--- a/src/pipecat/pipeline/task.py
+++ b/src/pipecat/pipeline/task.py
@@ -46,6 +46,7 @@ from pipecat.observers.turn_tracking_observer import TurnTrackingObserver
 from pipecat.pipeline.base_task import BasePipelineTask, PipelineTaskParams
 from pipecat.pipeline.pipeline import Pipeline, PipelineSink, PipelineSource
 from pipecat.pipeline.task_observer import TaskObserver
+from pipecat.processors.aggregators.llm_response import LLMUserContextAggregator
 from pipecat.processors.frame_processor import FrameDirection, FrameProcessor, FrameProcessorSetup
 from pipecat.utils.asyncio.task_manager import BaseTaskManager, TaskManager, TaskManagerParams
 from pipecat.utils.tracing.setup import is_tracing_available
@@ -704,7 +705,7 @@ class PipelineTask(BasePipelineTask):
             report_only_initial_ttfb=self._params.report_only_initial_ttfb,
             interruption_strategies=self._params.interruption_strategies,
         )
-        start_frame.metadata = self._params.start_metadata
+        start_frame.metadata = self._create_start_metadata()
         await self._pipeline.queue_frame(start_frame)
 
         # Wait for the pipeline to be started before pushing any other frame.
@@ -860,6 +861,7 @@ class PipelineTask(BasePipelineTask):
         return True
 
     async def _load_observer_files(self):
+        """Dynamically load observers from files listed in PIPECAT_OBSERVER_FILES."""
         observer_files = os.environ.get("PIPECAT_OBSERVER_FILES", "").split(":")
         for f in observer_files:
             try:
@@ -885,3 +887,26 @@ class PipelineTask(BasePipelineTask):
         tasks = [t.get_name() for t in self._task_manager.current_tasks()]
         if tasks:
             logger.warning(f"Dangling tasks detected: {tasks}")
+
+    def _create_start_metadata(self) -> Dict[str, Any]:
+        """Build and return start metadata including user-provided values."""
+        start_metadata = {}
+
+        # NOTE(aleix): Remove when OpenAILLMContext/LLMUserContextAggregator is removed.
+        if self._find_deprecated_openaillmcontext(self._pipeline):
+            start_metadata["deprecated_openaillmcontext"] = True
+
+        # Update with user provided metadata.
+        start_metadata.update(self._params.start_metadata)
+
+        return start_metadata
+
+    def _find_deprecated_openaillmcontext(self, processor: FrameProcessor) -> bool:
+        """Check whether there is a deprecated LLMUserContextAggregator in the pipeline."""
+        if isinstance(processor, LLMUserContextAggregator):
+            return True
+
+        for p in processor.processors:
+            if self._find_deprecated_openaillmcontext(p):
+                return True
+        return False
diff --git a/src/pipecat/processors/frame_processor.py b/src/pipecat/processors/frame_processor.py
index 0a7e2751e..09ec36b9a 100644
--- a/src/pipecat/processors/frame_processor.py
+++ b/src/pipecat/processors/frame_processor.py
@@ -196,6 +196,7 @@ class FrameProcessor(BaseObject):
         # Other properties (deprecated)
         self._allow_interruptions = False
         self._interruption_strategies: List[BaseInterruptionStrategy] = []
+        self._deprecated_openaillmcontext = False
 
         # Indicates whether we have received the StartFrame.
         self.__started = False
@@ -794,6 +795,9 @@ class FrameProcessor(BaseObject):
         self._interruption_strategies = frame.interruption_strategies
         self._report_only_initial_ttfb = frame.report_only_initial_ttfb
 
+        # NOTE(aleix): Remove when OpenAILLMContext/LLMUserContextAggregator is removed.
+        self._deprecated_openaillmcontext = "deprecated_openaillmcontext" in frame.metadata
+
         self.__create_process_task()
 
     async def __cancel(self, frame: CancelFrame):
diff --git a/src/pipecat/transports/base_input.py b/src/pipecat/transports/base_input.py
index 14a6b547f..b34eadfb8 100644
--- a/src/pipecat/transports/base_input.py
+++ b/src/pipecat/transports/base_input.py
@@ -394,7 +394,7 @@ class BaseInputTransport(FrameProcessor):
 
     async def _handle_vad(self, audio_frame: InputAudioRawFrame, vad_state: VADState) -> VADState:
         """Handle Voice Activity Detection results and generate appropriate frames."""
-        if self._params.turn_analyzer:
+        if self._params.turn_analyzer or self._deprecated_openaillmcontext:
             return await self._deprecated_handle_vad(audio_frame, vad_state)
         else:
             return await self._new_handle_vad(audio_frame, vad_state)