V2 Flux keepalive mechanism unclear - connections timeout after ~20-30s silence

[Shahid-Mo]

Summary

I'm experiencing connection timeouts with V2 Flux (listen.v2.connect) after 20-30 seconds of silence in a production voice AI application. I've tried multiple approaches based on existing documentation and GitHub issues, but haven't found a working solution. This issue documents my attempts and requests clarification on the recommended keepalive approach for V2 Flux.

What happened?

Actual:

• V2 Flux WebSocket connection closes after ~20-30 seconds of silence with keepalive ping timeout error
• Attempted JSON KeepAlive messages ({"type": "KeepAlive"}) → connection immediately dies with error 1005
• Attempted WebSocket protocol pings (connection._websocket.ping()) every 10s → still times out after 20-30s
• Attempted DeepgramClientOptions(options={"keepalive": "true"}) → ImportError (doesn't exist in SDK v5)
• Attempted control messages from PR feat: mention keep alive in migration guide #594 (ListenV1ControlMessage) → ModuleNotFoundError (deepgram.extensions doesn't exist)
• No documented keepalive mechanism for V2 Flux in docs or migration guides

Expected:

• Connection should stay alive during natural conversation pauses (60+ seconds)
• Clear documentation on how to implement keepalive for V2 Flux connections
• OR documentation stating V2 Flux doesn't support keepalive if that's the case

Context:
V2 Flux is perfect for conversational AI with automatic turn detection, but real conversations have natural pauses (users thinking, reading, distracted). A ~20-30s timeout makes multi-turn applications fragile. The Audio Keep Alive docs and PR #594 migration guide only cover V1, leaving V2 Flux users without guidance.

Steps to reproduce

1. Install deepgram-sdk==5.3.1
2. Create a V2 Flux WebSocket connection using client.listen.v2.connect(model="flux-general-en")
3. Send some audio, receive transcription (works fine)
4. Wait 30 seconds without sending any audio (simulating user pause)
5. Attempt to send audio again
6. Observe ConnectionClosedError: sent 1011 (internal error) keepalive ping timeout

Attempted workarounds (all failed):

Workaround 1: JSON KeepAlive

• Send await connection._send({"type": "KeepAlive"}) every 10s
• Result: Connection immediately closes with error 1005

Workaround 2: WebSocket pings

• Send await connection._websocket.ping() every 10s
• Result: Pings execute successfully but connection still times out after ~20-30s

Workaround 3: DeepgramClientOptions config

• Use DeepgramClientOptions(options={"keepalive": "true"})
• Result: ImportError - class doesn't exist in v5

Workaround 4: Control messages

• Import from deepgram.extensions.types.sockets import ListenV1ControlMessage
• Result: ModuleNotFoundError - module doesn't exist in SDK

Minimal code sample

import asyncio
from deepgram import AsyncDeepgramClient

async def test_timeout():
    client = AsyncDeepgramClient(api_key="YOUR_KEY")

    async with client.listen.v2.connect(
        model="flux-general-en",
        encoding="linear16",
        sample_rate=16000,
    ) as connection:
        print("Connected to Flux")

        # Simulate user asking a question and getting response
        # (works fine)
        audio_chunk = b'\x00' * 320  # 20ms of silence
        await connection.send_media(audio_chunk)
        await asyncio.sleep(2)  # Wait for response

        # Simulate user pausing to think (natural conversation)
        print("User pausing for 30 seconds...")
        await asyncio.sleep(30)

        # Try to send audio after pause
        print("Attempting to send audio after pause...")
        try:
            await connection.send_media(audio_chunk)
            print("✓ Audio sent successfully")
        except Exception as e:
            print(f"✗ Failed to send audio: {e}")
            # ConnectionClosedError: sent 1011 (internal error) keepalive ping timeout

asyncio.run(test_timeout())

Logs / traceback

2026-01-23 19:27:57 - INFO - ✅ Connected to Deepgram Flux
2026-01-23 19:28:00 - INFO - ✓ STT final: 'Capital of Australia.'
2026-01-23 19:28:04 - INFO - ✓ Turn complete - back to listening
2026-01-23 19:28:07 - INFO - 💓 Sent WebSocket ping to STT
2026-01-23 19:28:17 - INFO - 💓 Sent WebSocket ping to STT
2026-01-23 19:28:27 - INFO - 💓 Sent WebSocket ping to STT
2026-01-23 19:28:37 - INFO - 💓 Sent WebSocket ping to STT
2026-01-23 19:28:47 - INFO - 💓 Sent WebSocket ping to STT
2026-01-23 19:28:47 - WARNING - ⚠️ STT connection closed: None
2026-01-23 19:28:57 - ERROR - Future exception was never retrieved
future: <Future finished exception=ConnectionClosedError(None, Close(code=<CloseCode.INTERNAL_ERROR: 1011>, reason='keepalive ping timeout'), None)>
Traceback (most recent call last):
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/websockets/legacy/protocol.py", line 1276, in close_connection
    await self.transfer_data_task
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/websockets/legacy/protocol.py", line 951, in transfer_data
    await asyncio.shield(self._put_message_waiter)
asyncio.exceptions.CancelledError

The above exception was the direct cause of the following exception:

websockets.exceptions.ConnectionClosedError: sent 1011 (internal error) keepalive ping timeout; no close frame received

Error in Twilio WebSocket: sent 1011 (internal error) keepalive ping timeout; no close frame received
Traceback (most recent call last):
  [... same as above ...]
  File "/Users/shahid/dev/Projects/voice_ai/src/voice_ai/services/voice_session.py", line 186, in handle_audio_chunk
    await self.stt_connection.send_media(pcm_chunk)
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/deepgram/listen/v2/socket_client.py", line 59, in send_media
    await self._send(message)
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/deepgram/listen/v2/socket_client.py", line 82, in _send
    await self._websocket.send(data)
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/websockets/legacy/protocol.py", line 618, in send
    await self.ensure_open()
  File "/Users/shahid/dev/Projects/voice_ai/.venv/lib/python3.12/site-packages/websockets/legacy/protocol.py", line 925, in ensure_open
    raise self.connection_closed_exc()
websockets.exceptions.ConnectionClosedError: sent 1011 (internal error) keepalive ping timeout; no close frame received

Transport

WebSocket

API endpoint / path

wss://api.deepgram.com/v2/listen

Model(s) used

flux-general-en

How often?

Always

Is this a regression?

• Yes, it worked in an earlier version

Last working SDK version (if known)

No response

SDK version

5.3.1

Python version

3.12

Install method

uv

OS

macOS (Apple Silicon)

Environment details

- FastAPI application with async WebSocket handlers
- Twilio Media Streams integration (phone call audio)
- Async architecture using AsyncDeepgramClient
- Real-time bidirectional audio streaming (Twilio μ-law 8kHz ↔ PCM 16kHz)

Link to minimal repro (optional)

No response

Session ID (optional)

No response

Project ID (optional)

No response

Request ID (optional)

No response

Code of Conduct

• I agree to follow this project’s Code of Conduct