Siphon is an open-source framework that abstracts the complexity of building AI calling agents, letting developers ship voice AI in hours instead of weeks.
The Developer Problem
Building AI calling agents requires deep expertise in:
- SIP signaling and telephony infrastructure
- Real-time WebRTC audio streaming
- Orchestrating LLM, STT, and TTS services with sub-500ms latency
- Managing interruptions, state, and async event handling
- Implementing call persistence and monitoring
Most development teams spend 2–4 weeks just setting up infrastructure—before writing any conversation logic.
The Solution
Siphon provides a batteries-included framework. Here’s a complete, production-ready AI receptionist:
from siphon.agent import Agent
from siphon.plugins import openai, cartesia, deepgram
agent = Agent(
agent_name="receptionist",
llm=openai.LLM(),
tts=cartesia.TTS(),
stt=deepgram.STT(),
system_instructions="You are a helpful receptionist..."
)
if __name__ == "__main__":
agent.start() # Handles real PSTN calls
That’s it.
Deploy it—and it answers real phone calls.
Architecture
- Built on LiveKit (WebRTC transport layer)
- Native SIP integration for PSTN connectivity
- Streaming audio pipeline for <500ms voice-to-voice latency
- Plugin system for AI providers (OpenAI, Anthropic, Groq, etc.)
- Horizontal auto-scaling with zero configuration
- Automatic transcript, recording, and metadata persistence
Technical Highlights
- Vendor-agnostic: Swap LLM / STT / TTS providers via config
- Self-hosted: Apache 2.0 license — you own the infrastructure
- Production-ready: Built-in monitoring, error handling, and state management
- Developer-friendly: Type hints, clean APIs, and comprehensive docs
Perfect For Building
- Customer support automation
- Appointment scheduling systems
- Sales qualification pipelines
- Healthcare intake workflows
- Any telephony + AI use case
Why We Built It
After months spent wrangling SIP infrastructure for a voice AI project, we realized every developer building calling agents hits the same walls.
Siphon removes these barriers.
Repo & Docs
License: Apache 2.0