OpenRing

OpenRing is a self-hosted toolkit for building voice agents that can answer or place phone calls. Its project documentation describes a Vapi-compatible API, a browser test flow, and connections through carriers such as Twilio and Telnyx or through SIP.

The toolkit lets you choose providers for speech recognition, language models, and voice output. The project also documents a local setup using Whisper, Ollama, and Kokoro. Which pieces can run locally depends on your deployment and hardware. Phone traffic still needs a suitable connection if you move from a browser test to a real number.

OpenRing is MIT-licensed and has no per-minute platform fee. Compare the costs of your phone carrier, hosting, and any paid model or speech service before moving an existing workflow. If you use the Vapi-compatible API to migrate a setup, test each endpoint and callback that your integration relies on.

For an initial evaluation, set up a browser-only assistant with a short script. Read out a date and an alphanumeric reference, interrupt the assistant once, and compare its transcript with what you said. Check the same scenario on an authorized number before using it in a customer workflow.

Read the installation and provider documentation.