Patter

Patter is an open-source SDK for voice AI that gives an AI agent a phone number and connects it to real phone calls. It is presented as a Python and TypeScript tool, licensed under MIT, and it is aimed at developers building agents that can handle phone conversations.

The SDK supports both inbound and outbound calls with the same handler. Its listed features include native scheduling, voicemail detection, DTMF, function calls during a conversation, barge-in, call transfer to a human, and recording to disk or S3. Patter also describes two voice modes: end-to-end engines such as OpenAI Realtime and ElevenLabs ConvAI, and a pluggable pipeline mode with multiple STT, LLM, and TTS providers. The site also highlights sub-500 ms time-to-first-audio in Realtime mode, native 16 kHz streaming, frame-level buffering, and first-flush optimization.

For development, Patter includes a terminal test mode and a mode where tunnel: true spawns a Cloudflare tunnel so the agent can receive real calls. A built-in dashboard shows live call metrics, transcripts, call history, and per-segment costs, and it can export data to CSV or JSON with date filters. The page also shows that it is built to slot into Twilio, Telnyx, OpenAI Realtime, ElevenLabs, Deepgram, Anthropic, and Cartesia.

Patter is available as Python SDK and TypeScript SDK installs through pip or npm, and the page also refers to Patter Cloud as a hosted runtime with managed carriers. The site offers a waitlist and links to docs, changelog, GitHub, and a demo.