Is SIPHON really free?

Yes. SIPHON is 100% open-source under the Apache 2.0 license. You never pay us a platform fee. You only pay for your own infrastructure and the AI/Telephony providers you choose (e.g., OpenAI, Twilio).

Do I need to be a VoIP expert?

Not at all. SIPHON abstracts away the complex SIP signaling and media handling. If you're comfortable with Python, you can build production-grade voice agents.

Which AI models can I use with SIPHON?

You have total freedom. SIPHON supports OpenAI, Anthropic, Gemini, Groq, and open-source models via Ollama. You can swap providers with a single line of code.

How does SIPHON handle latency?

SIPHON is optimized for real-time performance. By hosting it on your own infrastructure (close to your users) and using WebSocket streams, you eliminate the additional hop and latency overhead of managed platforms.

Can I scale SIPHON to thousands of calls?

Yes. SIPHON is built on top of LiveKit, which powers massive scale streaming. The worker architecture allows you to horizontal scale your agent fleet to handle any volume.

How does SIPHON compare to closed platforms like Vapi or Retell?

Those are managed platforms that charge a markup per minute (often $0.05-$0.10/min). SIPHON gives you the same capabilities but runs on your own infrastructure, costing just the raw provider fees (typically ~$0.005-$0.02/min) and giving you full code control.

SIPHON: The Telephony-First Framework for Calling AI

Building an AI that can chat via text is now a solved problem. Building an AI that can handle a real phone call in production is still a nightmare of fragmented infrastructure.

Developers typically face a "plumbing" crisis: they must manually stitch together SIP trunks, manage real-time media buffers, handle signal interruptions, and wire up multiple AI providers—all while trying to keep latency low enough for a human conversation.

SIPHON was built to end the plumbing. It is an open-source Python framework that provides a unified, telephony-first abstraction for building and operating Calling AI agents.

The Problem: The Telephony Gap

Traditional IVR systems and contact center platforms were never designed for the era of Large Language Models (LLMs). When developers try to build modern calling agents, they encounter three primary friction points:

Complexity: Each project requires re-implementing SIP trunk provisioning, room orchestration, and VAD (Voice Activity Detection) tuning.
Vendor Lock-in: Most "Voice AI" platforms tie you to a single stack, making it impossible to swap LLM or TTS providers as technology evolves.
Operation Hurdles: Features like call recording, metadata persistence, and transcription handling are often treated as afterthoughts rather than first-class features.

The Solution: A Unified Calling Abstraction

SIPHON sits between the telephony world and the AI world, providing a coherent framework for developers to build production-ready agents in ~30 lines of code.

How it Works: The SIPHON Architecture

Unlike generic voice frameworks, SIPHON is built on top of LiveKit, leveraging its real-time media and SIP layer to ensure high reliability.

SIPHON High-Level Architecture

The diagram illustrates how SIPHON orchestrates the entire call lifecycle:

PSTN/SIP Provider ↔ LiveKit SIP Domain (Real-time media)
LiveKit Rooms ↔ SIPHON Agent Worker (Orchestration)
SIPHON Worker ↔ AI Providers (OpenAI, Deepgram, Cartesia, etc.)

The framework is divided into two core modules:

siphon.telephony: Handles inbound Dispatch rules and outbound Call initiation, allowing you to bind phone numbers to agents programmatically.
siphon.agent: The runner that manages the LiveKit Agent worker, entrypoint orchestration, and the dynamic construction of AI components.

Key Pillars of SIPHON

1. Production-Ready at Scale

SIPHON is not a "toy" framework. It is designed for horizontal scalability; you can run your agent on one server or a thousand, and the architecture automatically balances the load.

2. Sub-500ms Latency

By utilizing WebRTC for real-time media interactions, SIPHON ensures voice interactions feel natural. It manages audio packet loss and interruptions to maintain a human-like flow.

3. Total Vendor Flexibility

Through its plugin architecture, SIPHON is agnostic to your AI stack. You can swap between OpenAI, Gemini, Deepgram, or ElevenLabs with minimal code changes.

4. Integrated Data Persistence

Recording, transcription, and metadata persistence are enabled via simple environment flags. Whether you need to save to S3, Postgres, or Redis, SIPHON handles the storage logic for you.

Getting Started

SIPHON is now open-source under the Apache 2.0 license.

Developers can install the framework and spin up a functioning agent worker in minutes:

pip install siphon-ai

Whether you are building an AI receptionist, an outbound notification system, or a contact-center triage bot, SIPHON provides the infrastructure to get you to production faster.

Stop building the plumbing. Start building the agent.

📚 Read the Documentation | ⭐ Star us on GitHub

A BLACKDWARF Initiative.