Fonoster

Telephony bolted onto an application usually arrives as a metered vendor API. Fonoster offers an open source alternative to Twilio, a programmable telecommunications stack connecting telephony services to the internet through a cloud-based utility, for businesses that want call handling on their own terms.

A Voice Application here is a server that controls the flow of a call, written with the Node.js SDK. Verbs such as answer, say, gather, dial, record and hangup compose the logic, speech is synthesized through Google Speech APIs, and a bidirectional stream carries audio both ways. Everything is API first, so originating a call is a handful of lines through the same SDK.

The platform covers the operational surface a phone system needs.

• Multitenancy: separate tenants served from a single deployment.
• PBX features: private branch exchange functionality deploys without manual assembly.
• Access control: OAuth2 and JWT authentication paired with role-based access control.
• Secure endpoints: API endpoints protected with Let's Encrypt certificates.
• Storage: recordings and media held through Amazon S3 support.

A plugin-based command-line tool handles administration, and self-hosting is documented as a Docker deployment. The project describes itself as researching this stack and still frames onboarding through an early access quickstart, so treat it as a platform under active development rather than a settled product. Development happens in the open, with issues and discussion on GitHub and a sizable Discord community around it.