The open-source Voice AI SDK

by Patter

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🔊 Patter is the open-source way to connect any AI agent to real phone calls. Build voice-powered agents with a few lines of code — without managing telephony, speech pipelines, or audio infrastructure.

Visit the Patter docs to get started. SDK: Python / TypeScript

🧐 What is Patter?

Patter is a dual SDK (Python + TypeScript) that gives developers a unified API for the entire voice AI pipeline — speech-to-text, AI reasoning, text-to-speech, and telephony — wired together with sub-second latency so your agent sounds natural on a real phone call.

✨ Just like this

import asyncio
from patter import Patter

async def main():
    phone = Patter(
        openai_key="sk-...",
        phone_number="+15550001234",
        webhook_url="your.server.com",
    )

    agent = phone.agent(
        system_prompt="You are a friendly booking assistant for a dental clinic.",
        voice="nova",
        first_message="Hi! I'm calling from Smile Dental. How can I help?",
    )

    await phone.serve(agent, port=8000)

asyncio.run(main())

🚀 Key Features

• 📞 Inbound & Outbound Calls — answer calls or dial out programmatically with Twilio or Telnyx
• ⚡ 3 Voice Modes — OpenAI Realtime (lowest latency), Pipeline (custom STT+TTS), ElevenLabs ConvAI
• 🔧 Tool Calling — let your agent check databases, book appointments, or transfer calls
• 📊 Built-in Dashboard — real-time call monitoring, cost tracking, and analytics
• 🧪 Test Mode — develop agents in your terminal, no phone needed
• 💰 Per-Call Metrics — cost breakdown by provider (STT, TTS, LLM, telephony) with latency percentiles
• 🛡️ Guardrails — content filtering and blocked terms before speech output
• 🏠 Local Mode — runs entirely on your machine, no cloud dependency
• 🤖 Any LLM — pluggable LLM loop, bring your own Anthropic, Gemini, or any provider

🏁 Getting Started

• 📥 Installation — install the SDK and set up your environment
• 📖 Documentation — full guides for Python and TypeScript
• 💬 Discussions — ask questions and share what you've built
• 🐛 Issues — report bugs or suggest features