feat: add Vonage Audio Connector integration (serializer, transport, foundational example)

[varunps2003]

Summary

This PR introduces the Vonage Audio Connector integration including a custom serializer, the VonageAudioConnectorTransport + VonageAudioConnectorOutputTransport and a foundational example.

Changes

• Added foundational example: examples/foundational/49-vonage-audio-connector-openai.py
• Added VonageFrameSerializer under src/pipecat/serializers/vonage.py
• Added VonageAudioConnectorTransport and VonageAudioConnectorOutputTransport under src/pipecat/transports/vonage/audio_connector.py
• Added new package folder src/pipecat/transports/vonage/ with __init__.py
• Updated env.example
• Updated pyproject.toml and uv.lock

Why This Is Needed

This integration enables Pipecat to work with the Vonage Voice API Audio Connector supporting real-time STT → LLM → TTS pipelines and will be used to expand the ecosystem of community-maintained integrations.

Testing

• Basic end-to-end pipeline validated (audio in → STT → LLM → TTS → audio out)
• Serializer and transport tested for encoding/decoding correctness
• Verified pacing behavior (sleep-per-chunk timing) matches Vonage Audio Connector requirements
• Confirmed WAV-header wrapping when enabled

[varunps2003]

Hi @jamsea
I’ve created the PR for the Vonage Audio Connector integration (serializer, transport, foundational example).
Please take a look whenever you get a chance — happy to make any changes needed. Thanks!

[varunps2003]

I’ve just pushed a follow-up commit to switch the foundational example from the dev OpenTok API URL to the production https://api.opentok.com.

[varunps2003]

Hi @markbackman and @filipi87 Can you please find sometime to review this PR.

[markbackman]

Sorry for the delay. We're backlogged on PR reviews. I took a quick look at this and think it's a good plan to split it up. First, can you create a PR for only the VonageFrameSerializer? Along with this, it would be helpful to submit an example for pipecat-examples showing how to dial-in and dial-out. This would be similar to the examples that exist for Twilio, Telnyx, Plivo, and Exotel.

That's a big enough change to add and test that I think we should start there. It will also help developers get started right away as they can easily test and run the example. WDYT?

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The VonageFrameSerializer should be written to work with the FastAPIWebsocketTransport. Is there a reason to add a new websocket transport to work specifically with the VonageFrameSerializer?