The missing infrastructure layer for AI calling. Siphon handles state, interruptions, and scaling so you can ship reliable agents in minutes. Open Source.

Calling

SIPHON supports both inbound and outbound calling.

At a high level, SIPHON is responsible for:

Building the agent worker (LLM/STT/TTS + instructions) that joins a call session.
Creating the telephony routing (trunks + dispatch) so PSTN calls can reach that worker.

The underlying SIP transport and media bridging is handled by the realtime/telephony layer under the hood, while SIPHON focuses on orchestration and a simple Python API.

Inbound calling: receive calls to a phone number and route them to an agent
Outbound calling: place calls from code and connect them to an agent

End-to-end flow diagrams

Inbound flow (someone calls your number)

Inbound calling flow

Provider-specific SIP examples (Twilio, Telnyx, Plivo, Wavix): Provider-specific quickstarts

In SIPHON terms:

You run the worker with Agent(...).
You configure routing with Dispatch(...).agent().

Outbound flow (your code places the call)

Outbound calling flow

In SIPHON terms:

Your worker is still the same Agent(...) process.
Your application triggers dialing via Call(...).start().

What gets passed to the worker?

Both inbound and outbound flows attach metadata that includes an agent_config payload (LLM/STT/TTS config + instructions). The worker reads this metadata when it receives a job and reconstructs the runtime components.