# Voice and Video for Android

This guide provides a detailed description of the Sinch Android SDK components and how they work together. Refer here when you need a deeper understanding of responsibilities, lifecycles, and integration points.

- SinchClient: The primary entry point to the SDK; manages configuration, authentication, and feature controllers.
- CallController: Exposes APIs to place and receive calls, and notifies about incoming call events.
- Call: Represents an active call with methods for answering, declining, and hanging up. Access point to `CallListener` which emits state changes (progressing, ringing, answered, established, ended).
- PushConfiguration: Configures FCM or HMS for incoming call notifications when the app is backgrounded.
- Listeners: `SinchClientListener`, `CallControllerListener`, and `CallListener` provide callbacks for state and events.
- Call Quality: `CallQualityWarningEventListener` reports network and media quality indicators (e.g., jitter, packet loss, MOS hints) so you can monitor and react (surface indicators in UI, switch networks or warn users). Attach to the `Call` object to receive the updates.
- Authentication (JWT): Use a backend‑generated, secret‑signed JWT to authorize the client; never embed secrets in the app.


For API details, see the [Reference Documentation](https://download.sinch.com/android/latest/reference/index.html).

First time here?
If you're new and want to quickly try the SDK, start with the Android Getting Started guide: [Create an app](/docs/in-app-calling/getting-started/android/create-app).

## Reference Application

Explore a complete Android reference application that demonstrates common use cases:

- App to App Calling (audio and video)
- App to PSTN Calling
- App to SIP Calling


Find the Android reference application on GitHub: [rtc-reference-applications (Android)](https://github.com/sinch/rtc-reference-applications/tree/master/android)

Browse all Sinch sample and reference applications: [rtc-reference-applications (root)](https://github.com/sinch/rtc-reference-applications)