Awesome Open Source
Awesome Open Source

Fonoster: The open-source alternative to Twilio

Fonoster Inc researches an innovative Programmable Telecommunications Stack that will allow for an entirely cloud-based utility for businesses to connect telephony services with the Internet.

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The most notable features on FN 0.3 are:

  • [x] Cloud initialization with Cloud-Init
  • [x] Multitenancy
  • [x] Easy deployment of PBXs functionalities
  • [x] Programmable Voice Applications
  • [x] NodeJS SDK
  • [x] Web SDK
  • [x] Support for Amazon Simple Storage Service (S3)
  • [x] Secure API endpoints with Let's Encrypt
  • [x] Authentication with OAuth2
  • [X] Authentication with JWT
  • [x] Role-Based Access Control (RBAC)
  • [x] Plugins-based Command-line Tool
  • [x] Support for Google Speech API
  • [x] Experimental support for Cloud Functions
  • [x] Experimental support for Secret management

Code Examples

A Voice Application is a server that takes control of the flow in a call. A Voice Application can use any combination of the following verbs:

  • Answer - Accepts an incoming call
  • Hangup - Closes the call
  • Play - Takes an URL or file and streams the sound back to the calling party
  • Say - Takes a text, synthesizes the text into audio, and streams back the result
  • Gather - Waits for DTMF or speech events and returns back the result
  • SGather - Returns a stream for future DTMF and speech results
  • Dial - Passes the call to an Agent or a Number at the PSTN
  • Record - It records the voice of the calling party and saves the audio on the Storage sub-system
  • Mute - It tells the channel to stop sending media, effectively muting the channel
  • Unmute - It tells the channel to allow media flow

Voice Application Example:

const { VoiceServer } = require("@fonoster/voice");

const serverConfig = {
  pathToFiles: `${process.cwd()}/sounds`,

new VoiceServer(serverConfig).listen(
  async (req, res) => {
    await res.answer();
    await res.hangup();

// your app will live at 
// and you can easily publish it to the Internet with:
// ngrok http 3000

Everything in FN is an API first, and initiating a call is no exception. You can use the SDK to start a call with a few lines of code.

Example of originating a call with the SDK:

const Fonoster = require("@fonoster/sdk");
const callManager = new Fonoster.CallManager();{
 from: "9842753574",
 to: "17853178070",
 webhook: ""

Getting Started

To get started with FN use the following resources:

Give a Star!

If you like this project or plan to use it in the future, please give it a star. Thanks

Bugs and Feedback

For bugs, questions, and discussions, please use the Github Issues


For contributing, please see the following links:


We're glad to be supported by respected companies and individuals from several industries.

Find all our supporters here

Become a Github Sponsor



Copyright (C) 2022 by Fonoster Inc. MIT License (see LICENSE for details).

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