Building AI calling agents shouldn't require a commercial license or massive per-minute markups.

If you are a Python developer, you should be able to spin up a sub-500ms latency voice agent on your own machine.

Today, I'm going to introduce you to Siphon, an open-source (Apache 2.0) Python framework built by BLACKDWARF that natively bridges SIP trunks to LLMs.

Prerequisites

Python 3.10+

A Twilio or Telnyx SIP Trunk

LiveKit Credentials

An OpenAI API Key

Step 1: Installation & Setup

First, clone the Siphon repository and install the requirements.

pip install siphon-ai

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Next, create a .env file in your project root to hold your raw provider keys.

Because Siphon is self-hosted, you pay providers like OpenAI and LiveKit directly—NO MIDDLEMAN FEES.

LIVEKIT_URL = wss://your-project.livekit.cloud LIVEKIT_API_KEY = your_livekit_key LIVEKIT_API_SECRET = your_livekit_secret OPENAI_API_KEY = sk-yourkey DEEPGRAM_API_KEY = yourkey FROM_NUMBER = +15551234567…