.NET Library for OpenAI SIP End Point

This repository contains a .NET library for interacting with OpenAI's real-time SIP API. It provides helper classes to establish SIP calls with the endpoint.

This library is currently a work in progress and there is no official release yet.

Status (05 Sep 2025)

The example in examples/GetStarted is now working end-to-end:

• Places a SIP TLS call to sip.api.openai.com using your OpenAI Project ID.
• Receives the webhook (after you expose /webhook publicly, e.g. via ngrok).
• Accepts the call and upgrades to a realtime WebSocket session.
• Sends an initial instruction and logs incoming realtime events.

See the README in examples/GetStarted for setup (environment variables, ngrok, run instructions).

Note: Audio currently negotiates PCM; Opus not yet established in testing. No echo cancellation—use a headset.

License

Distributed under the BSD 3‑Clause license with an additional BDS BY‑NC‑SA restriction. See LICENSE.md for details.