Merge pull request #1634 from pipecat-ai/mb/twilio-end-call

Automatically hangup Twilio calls

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added automatic hangup logic to the Twilio serializer. This feature hangs up
+  the Twilio call when an `EndFrame` or `CancelFrame` is received. It is
+  enabled by default and is configurable via the `auto_hang_up` `InputParam`.
+
 - Added `SmartTurnMetricsData`, which contains end-of-turn prediction metrics,
   to the `MetricsFrame`. Using `MetricsFrame`, you can now retrieve prediction
   confidence scores and processing time metrics from the smart turn analyzers.
@@ -80,6 +84,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed an issue where LLM input parameters were not working and applied correctly in `GoogleVertexLLMService`, causing
   unexpected behavior during inference.
 
+### Other
+
+- Updated the `twilio-chatbot` example to use the auto-hangup feature.
+
 ## [0.0.63] - 2025-04-11
 
 ### Added

dot-env.template

@@ -97,3 +97,7 @@ PIPER_BASE_URL=...
 # Smart turn
 LOCAL_SMART_TURN_MODEL_PATH=
 REMOTE_SMART_TURN_URL=
+
+# Twilio
+TWILIO_ACCOUNT_SID=
+TWILIO_AUTH_TOKEN=

examples/twilio-chatbot/bot.py

@@ -54,7 +54,14 @@ async def save_audio(server_name: str, audio: bytes, sample_rate: int, num_chann
         logger.info("No audio data to save")
 
 
-async def run_bot(websocket_client: WebSocket, stream_sid: str, testing: bool):
+async def run_bot(websocket_client: WebSocket, stream_sid: str, call_sid: str, testing: bool):
+    serializer = TwilioFrameSerializer(
+        stream_sid=stream_sid,
+        call_sid=call_sid,
+        account_sid=os.getenv("TWILIO_ACCOUNT_SID", ""),
+        auth_token=os.getenv("TWILIO_AUTH_TOKEN", ""),
+    )
+
     transport = FastAPIWebsocketTransport(
         websocket=websocket_client,
         params=FastAPIWebsocketParams(
@@ -64,7 +71,7 @@ async def run_bot(websocket_client: WebSocket, stream_sid: str, testing: bool):
             vad_enabled=True,
             vad_analyzer=SileroVADAnalyzer(),
             vad_audio_passthrough=True,
-            serializer=TwilioFrameSerializer(stream_sid),
+            serializer=serializer,
         ),
     )
 

examples/twilio-chatbot/server.py

@@ -38,8 +38,9 @@ async def websocket_endpoint(websocket: WebSocket):
     call_data = json.loads(await start_data.__anext__())
     print(call_data, flush=True)
     stream_sid = call_data["start"]["streamSid"]
+    call_sid = call_data["start"]["callSid"]
     print("WebSocket connection accepted")
-    await run_bot(websocket, stream_sid, app.state.testing)
+    await run_bot(websocket, stream_sid, call_sid, app.state.testing)
 
 
 if __name__ == "__main__":

src/pipecat/serializers/twilio.py

@@ -8,11 +8,14 @@ import base64
 import json
 from typing import Optional
 
+from loguru import logger
 from pydantic import BaseModel
 
 from pipecat.audio.utils import create_default_resampler, pcm_to_ulaw, ulaw_to_pcm
 from pipecat.frames.frames import (
     AudioRawFrame,
+    CancelFrame,
+    EndFrame,
     Frame,
     InputAudioRawFrame,
     InputDTMFFrame,
@@ -26,12 +29,61 @@ from pipecat.serializers.base_serializer import FrameSerializer, FrameSerializer
 
 
 class TwilioFrameSerializer(FrameSerializer):
-    class InputParams(BaseModel):
+    """Serializer for Twilio Media Streams WebSocket protocol.
-        twilio_sample_rate: int = 8000  # Default Twilio rate (8kHz)
-        sample_rate: Optional[int] = None  # Pipeline input rate
 
-    def __init__(self, stream_sid: str, params: InputParams = InputParams()):
+    This serializer handles converting between Pipecat frames and Twilio's WebSocket
+    media streams protocol. It supports audio conversion, DTMF events, and automatic
+    call termination.
+
+    When auto_hang_up is enabled (default), the serializer will automatically terminate
+    the Twilio call when an EndFrame or CancelFrame is processed, but requires Twilio
+    credentials to be provided.
+
+    Attributes:
+        _stream_sid: The Twilio Media Stream SID.
+        _call_sid: The associated Twilio Call SID.
+        _account_sid: Twilio account SID for API access.
+        _auth_token: Twilio authentication token for API access.
+        _params: Configuration parameters.
+        _twilio_sample_rate: Sample rate used by Twilio (typically 8kHz).
+        _sample_rate: Input sample rate for the pipeline.
+        _resampler: Audio resampler for format conversion.
+    """
+
+    class InputParams(BaseModel):
+        """Configuration parameters for TwilioFrameSerializer.
+
+        Attributes:
+            twilio_sample_rate: Sample rate used by Twilio, defaults to 8000 Hz.
+            sample_rate: Optional override for pipeline input sample rate.
+            auto_hang_up: Whether to automatically terminate call on EndFrame.
+        """
+
+        twilio_sample_rate: int = 8000
+        sample_rate: Optional[int] = None
+        auto_hang_up: bool = True
+
+    def __init__(
+        self,
+        stream_sid: str,
+        call_sid: str,
+        account_sid: Optional[str] = None,
+        auth_token: Optional[str] = None,
+        params: InputParams = InputParams(),
+    ):
+        """Initialize the TwilioFrameSerializer.
+
+        Args:
+            stream_sid: The Twilio Media Stream SID.
+            call_sid: The associated Twilio Call SID.
+            account_sid: Twilio account SID.
+            auth_token: Twilio auth token.
+            params: Configuration parameters.
+        """
         self._stream_sid = stream_sid
+        self._call_sid = call_sid
+        self._account_sid = account_sid
+        self._auth_token = auth_token
         self._params = params
 
         self._twilio_sample_rate = self._params.twilio_sample_rate
@@ -41,13 +93,37 @@ class TwilioFrameSerializer(FrameSerializer):
 
     @property
     def type(self) -> FrameSerializerType:
+        """Gets the serializer type.
+
+        Returns:
+            The serializer type, either TEXT or BINARY.
+        """
         return FrameSerializerType.TEXT
 
     async def setup(self, frame: StartFrame):
+        """Sets up the serializer with pipeline configuration.
+
+        Args:
+            frame: The StartFrame containing pipeline configuration.
+        """
         self._sample_rate = self._params.sample_rate or frame.audio_in_sample_rate
 
     async def serialize(self, frame: Frame) -> str | bytes | None:
-        if isinstance(frame, StartInterruptionFrame):
+        """Serializes a Pipecat frame to Twilio WebSocket format.
+
+        Handles conversion of various frame types to Twilio WebSocket messages.
+        For EndFrames, initiates call termination if auto_hang_up is enabled.
+
+        Args:
+            frame: The Pipecat frame to serialize.
+
+        Returns:
+            Serialized data as string or bytes, or None if the frame isn't handled.
+        """
+        if self._params.auto_hang_up and isinstance(frame, (EndFrame, CancelFrame)):
+            await self._hang_up_call()
+            return None
+        elif isinstance(frame, StartInterruptionFrame):
             answer = {"event": "clear", "streamSid": self._stream_sid}
             return json.dumps(answer)
         elif isinstance(frame, AudioRawFrame):
@@ -68,7 +144,59 @@ class TwilioFrameSerializer(FrameSerializer):
         elif isinstance(frame, (TransportMessageFrame, TransportMessageUrgentFrame)):
             return json.dumps(frame.message)
 
+        # Return None for unhandled frames
+        return None
+
+    async def _hang_up_call(self):
+        """Hang up the Twilio call using Twilio's REST API."""
+        try:
+            import aiohttp
+
+            account_sid = self._account_sid
+            auth_token = self._auth_token
+
+            if not account_sid or not auth_token:
+                logger.warning(
+                    "Cannot hang up Twilio call: account_sid and auth_token must be provided"
+                )
+                return
+
+            # Twilio API endpoint for updating calls
+            endpoint = f"https://api.twilio.com/2010-04-01/Accounts/{account_sid}/Calls/{self._call_sid}.json"
+
+            # Create basic auth from account_sid and auth_token
+            auth = aiohttp.BasicAuth(account_sid, auth_token)
+
+            # Parameters to set the call status to "completed" (hang up)
+            params = {"Status": "completed"}
+
+            # Make the POST request to update the call
+            async with aiohttp.ClientSession() as session:
+                async with session.post(endpoint, auth=auth, data=params) as response:
+                    if response.status == 200:
+                        logger.info(f"Successfully terminated Twilio call {self._call_sid}")
+                    else:
+                        # Get the error details for better debugging
+                        error_text = await response.text()
+                        logger.error(
+                            f"Failed to terminate Twilio call {self._call_sid}: "
+                            f"Status {response.status}, Response: {error_text}"
+                        )
+
+        except Exception as e:
+            logger.exception(f"Failed to hang up Twilio call: {e}")
+
     async def deserialize(self, data: str | bytes) -> Frame | None:
+        """Deserializes Twilio WebSocket data to Pipecat frames.
+
+        Handles conversion of Twilio media events to appropriate Pipecat frames.
+
+        Args:
+            data: The raw WebSocket data from Twilio.
+
+        Returns:
+            A Pipecat frame corresponding to the Twilio event, or None if unhandled.
+        """
         message = json.loads(data)
 
         if message["event"] == "media":

src/pipecat/transports/network/fastapi_websocket.py

@@ -207,10 +207,12 @@ class FastAPIWebsocketOutputTransport(BaseOutputTransport):
 
     async def stop(self, frame: EndFrame):
         await super().stop(frame)
+        await self._write_frame(frame)
         await self._client.disconnect()
 
     async def cancel(self, frame: CancelFrame):
         await super().cancel(frame)
+        await self._write_frame(frame)
         await self._client.disconnect()
 
     async def cleanup(self):

src/pipecat/transports/network/websocket_server.py

@@ -157,7 +157,8 @@ class WebsocketServerInputTransport(BaseInputTransport):
         self, websocket: websockets.WebSocketServerProtocol, session_timeout: int
     ):
         """Wait for session_timeout seconds, if the websocket is still open,
-        trigger timeout event."""
+        trigger timeout event.
+        """
         try:
             await asyncio.sleep(session_timeout)
             if not websocket.closed:
@@ -195,6 +196,14 @@ class WebsocketServerOutputTransport(BaseOutputTransport):
         await self._params.serializer.setup(frame)
         self._send_interval = (self._audio_chunk_size / self.sample_rate) / 2
 
+    async def stop(self, frame: EndFrame):
+        await super().stop(frame)
+        await self._write_frame(frame)
+
+    async def cancel(self, frame: CancelFrame):
+        await super().cancel(frame)
+        await self._write_frame(frame)
+
     async def cleanup(self):
         await super().cleanup()
         await self._transport.cleanup()