> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cognigy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Cognigy Click To Call SDK

> Cognigy Click To Call SDK for WebRTC SIP voice calling in web apps and AI integration.

*Cognigy Click To Call SDK* is a JavaScript/TypeScript SDK for adding SIP-based voice calling to web applications using WebRTC. Built on [JsSIP](https://jssip.net/), the SDK provides APIs to manage voice sessions, SIP signaling, audio streams, and transcription.

The SDK is designed for developers building custom voice interfaces on top of the Cognigy.AI platform and Cognigy Voice Gateway.

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## What's in This SDK?

### SDK Purpose

The Click To Call SDK helps developers:

* Establish real-time voice calls between a user's browser and Cognigy Voice Gateway using SIP signaling and the WebRTC API.
* Manage the full call lifecycle through a simple, promise-based API.
* Handle remote audio playback automatically.
* Receive real-time transcription events during calls, with automatic separation from regular info messages.

### Requirements

| Requirement     | Details                                                                                                                     |
| --------------- | --------------------------------------------------------------------------------------------------------------------------- |
| Language        | JavaScript or TypeScript. The SDK works with any framework, including React, Angular, Vue, or vanilla JS.                   |
| Node.js         | 18 or later                                                                                                                 |
| Package manager | npm                                                                                                                         |
| Browsers        | Modern web and mobile browsers. For more information, refer to [Supported Browsers](/click-to-call/sdk/supported-browsers). |
| Network         | HTTPS or `localhost`. WebSocket and UDP traffic must be allowed.                                                            |
| Backend         | A Cognigy.AI Flow with a configured Voice Gateway Endpoint.                                                                 |

### Use Cases

* Build multimodal browser-based voice interfaces that connect to Cognigy AI Agents.
* Embed click-to-call functionality into web applications or customer portals.
* Display real-time transcription of voice conversations in your UI.
* Integrate voice calling into existing React, Angular, Vue, or vanilla JS applications without framework lock-in.

## Key Features

| Feature                   | Description                                                                                                                                                                                                                                                                        |
| ------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Custom Audio Handling     | The automatic audio playback uses an internal `Audio` element. For advanced use cases, enable `captureAudio: true` in the client config to receive the raw `MediaStream`. The `audioEnded` event signals when playback stops. See [Custom Audio](/click-to-call/sdk/custom-audio). |
| Full Call Control         | The complete call management includes start, end, mute, unmute, and info messages as async methods. See [API Reference](/click-to-call/sdk/api-reference/overview).                                                                                                                |
| Multimodality             | The multimodal interactions combine voice, text, and structured data in real time. The `sendInfo` method allows sending text and optional structured data during calls. See [API Reference: sendInfo](/click-to-call/sdk/api-reference/send-info).                                 |
| Event-Driven Architecture | The event system provides 17 events covering connection state, call state, audio, transcription, and errors. See [Event Reference](/click-to-call/sdk/event-reference/overview).                                                                                                   |
| Real-Time Transcription   | The transcription events are received during calls and automatically filtered from regular info messages. See [Event Reference: transcription](/click-to-call/sdk/event-reference/transcription).                                                                                  |

## Changelog Reference

The latest SDK version is available on npm as `@cognigy/click-to-call-sdk`. For updates and fixes, refer to the [Cognigy Click To Call SDK GitHub repository](https://github.com/Cognigy/click-to-call-sdk).

## License

The Cognigy Click To Call SDK is licensed under the MIT License.

## What's Next?

* [Install the SDK, create a client, and make your first voice call](/click-to-call/sdk/getting-started)
* [Learn how the SDK authenticates](/click-to-call/sdk/initialization)
* [Explore all methods, configuration options, and types](/click-to-call/sdk/api-reference/overview)
* [Discover events with callback signatures and examples](/click-to-call/sdk/event-reference/overview)
* [Transport encryption, credential handling, and best practices](/click-to-call/sdk/security)
* [Find solutions for common connection, call, and browser issues](/click-to-call/sdk/troubleshooting)