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+# Realtime Twilio Integration
+
+This example demonstrates how to connect the OpenAI Realtime API to a phone call using Twilio's Media Streams. The server handles incoming phone calls and streams audio between Twilio and the OpenAI Realtime API, enabling real-time voice conversations with an AI agent over the phone.
+
+## Prerequisites
+
+-   Python 3.10+
+-   OpenAI API key with [Realtime API](https://platform.openai.com/docs/guides/realtime) access
+-   [Twilio](https://www.twilio.com/docs/voice) account with a phone number
+-   A tunneling service like [ngrok](https://ngrok.com/) to expose your local server
+
+## Setup
+
+1. **Start the server:**
+
+    ```bash
+    uv run server.py
+    ```
+
+    The server will start on port 8000 by default.
+
+2. **Expose the server publicly, e.g. via ngrok:**
+
+    ```bash
+    ngrok http 8000
+    ```
+
+    Note the public URL (e.g., `https://abc123.ngrok.io`)
+
+3. **Configure your Twilio phone number:**
+    - Log into your Twilio Console
+    - Select your phone number
+    - Set the webhook URL for incoming calls to: `https://your-ngrok-url.ngrok.io/incoming-call`
+    - Set the HTTP method to POST
+
+## Usage
+
+1. Call your Twilio phone number
+2. You'll hear: "Hello! You're now connected to an AI assistant. You can start talking!"
+3. Start speaking - the AI will respond in real-time
+4. The assistant has access to tools like weather information and current time
+
+## How It Works
+
+1. **Incoming Call**: When someone calls your Twilio number, Twilio makes a request to `/incoming-call`
+2. **TwiML Response**: The server returns TwiML that:
+    - Plays a greeting message
+    - Connects the call to a WebSocket stream at `/media-stream`
+3. **WebSocket Connection**: Twilio establishes a WebSocket connection for bidirectional audio streaming
+4. **Transport Layer**: The `TwilioRealtimeTransportLayer` class owns the WebSocket message handling:
+    - Takes ownership of the Twilio WebSocket after initial handshake
+    - Runs its own message loop to process all Twilio messages
+    - Handles protocol differences between Twilio and OpenAI
+    - Automatically sets G.711 μ-law audio format for Twilio compatibility
+    - Manages audio chunk tracking for interruption support
+    - Wraps the OpenAI realtime model instead of subclassing it
+5. **Audio Processing**:
+    - Audio from the caller is base64 decoded and sent to OpenAI Realtime API
+    - Audio responses from OpenAI are base64 encoded and sent back to Twilio
+    - Twilio plays the audio to the caller
+
+## Configuration
+
+-   **Port**: Set `PORT` environment variable (default: 8000)
+-   **OpenAI API Key**: Set `OPENAI_API_KEY` environment variable
+-   **Agent Instructions**: Modify the `RealtimeAgent` configuration in `server.py`
+-   **Tools**: Add or modify function tools in `server.py`
+
+## Troubleshooting
+
+-   **WebSocket connection issues**: Ensure your ngrok URL is correct and publicly accessible
+-   **Audio quality**: Twilio streams audio in mulaw format at 8kHz, which may affect quality
+-   **Latency**: Network latency between Twilio, your server, and OpenAI affects response time
+-   **Logs**: Check the console output for detailed connection and error logs
+
+## Architecture
+
+```
+Phone Call → Twilio → WebSocket → TwilioRealtimeTransportLayer → OpenAI Realtime API
+                                              ↓
+                                      RealtimeAgent with Tools
+                                              ↓
+                           Audio Response → Twilio → Phone Call
+```
+
+The `TwilioRealtimeTransportLayer` acts as a bridge between Twilio's Media Streams and OpenAI's Realtime API, handling the protocol differences and audio format conversions. It wraps the OpenAI realtime model to provide a clean interface for Twilio integration.