## Calling API
When using Sinch for voice calling, the Sinch dashboard works as a big telephony switch. The dashboard handles incoming phone calls (also known as *incoming call “legs”*), sets up outgoing phone calls (or *outgoing call “legs”*), and bridges the two. The incoming call leg may come in over a data connection (from a smartphone or web application using the Sinch SDKs) or through a local phone number (from the PSTN network). Similarly, the outgoing call leg can be over data (to another smartphone or web application using the Sinch SDKs) or the PSTN network.
For most calls, you can use the [Sinch In-app Voice & Video SDKs](https://developers.sinch.com/docs/in-app-calling/index.md) on a smartphone or web client to establish calls without the need of additional integration. For more control or flexibility of the calls, you can use the Sinch REST APIs to manage the calls.
Controlling a call from your application is done by responding to callbacks from the Sinch platform and/or by calling REST APIs in the Sinch platform from your application. For more details on the callbacks triggered from the Sinch platform see the [Callback API](https://developers.sinch.com/docs/voice/api-reference/voice/callbacks).