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Python Quickstart

This guide walks you through building a voice AI agent that answers phone calls using local/self-hosted mode.

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Prerequisites

  • Python 3.11+
  • A telephony account (Twilio or Telnyx)
  • An AI provider key (OpenAI, ElevenLabs, or Deepgram)

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Step 1: Install the SDK

pip install patter[local]

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Step 2: Set Up Credentials

Create a .env file in your project root: 
TWILIO_SID=ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
TWILIO_TOKEN=your_auth_token
OPENAI_KEY=sk-xxxxxxxxxxxxxxxxxxxxxxxx
PHONE_NUMBER=+15550001234
WEBHOOK_URL=abc.ngrok.io

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Step 3: Expose Your Server

Patter needs a public URL so Twilio/Telnyx can reach your local server. Use ngrok: 
ngrok http 8000
Copy the hostname (e.g., abc.ngrok.io) and use it as your WEBHOOK_URL.

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Step 4: Write Your Agent

import os
import asyncio
from dotenv import load_dotenv
from patter import Patter

load_dotenv()

phone = Patter(
    twilio_sid=os.environ["TWILIO_SID"],
    twilio_token=os.environ["TWILIO_TOKEN"],
    openai_key=os.environ["OPENAI_KEY"],
    phone_number=os.environ["PHONE_NUMBER"],
    webhook_url=os.environ["WEBHOOK_URL"],
)

agent = phone.agent(
    system_prompt="You are a helpful assistant for a pizza restaurant. Help customers place orders and answer questions about the menu.",
    voice="alloy",
    first_message="Hi! Welcome to Pizza Palace. What can I get for you today?",
)

async def main():
    await phone.serve(agent, port=8000)

asyncio.run(main())

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Step 5: Make a Call

Call your PHONE_NUMBER from any phone. The AI agent will answer and start the conversation.

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What’s Next

Configuration

Explore all constructor options and modes.

Agents

Customize voice, model, and behavior.

Tools

Add function calling to your agent.

Events

Handle call start, end, and transcript events.