***

id: cc637856-c001-49e7-9763-766398f66d8c
title: SIP domain applications
slug: /voice/sip/domain-applications
x-custom:
author: rsowald
tags:

* 'product:voice'
* 'product:video'
* getting-started
  description: >-
  Learn about SIP Domain Applications on the SignalWire platform - send SIP
  traffic to a custom domain and run specified logic.

***

A Domain Application is a SignalWire feature that allows you to send SIP traffic to a custom domain and run specified logic. To define that logic, you can set up a handler in the SIP Space of your [SignalWire Dashboard](https://signalwire.com/signin).

<Frame caption="Domain App page with the option to create a new Domain App">
  ![Domain App page with the option to create a new Domain App](https://files.buildwithfern.com/signalwire.docs.buildwithfern.com/docs/61e03e30f582c9803176a9d569be4d6aed4b7a30e903fa3df6c6689742fd67fc/assets/images/dashboard/sip/sip-domain-apps.webp)
</Frame>

## RELAY Application

If you are handling incoming SIP traffic with a **RELAY Application**, you are defining
your logic in a separate RELAY application on your own server. RELAY applications run
different logic based on the topic (V4) or context (V3) attached to incoming calls, so you will need to choose
a topic/context to label your incoming SIP traffic. The following example shows a RELAY client
listening for the "office" topic/context then runs the logic inside the event listener callback.

<Tabs>
  <Tab title="RELAY V4">
    ```js
    import { SignalWire } from "@signalwire/realtime-api";

    const client = await SignalWire({
      project: "your-project-id",
      token: "your-api-token",
      // This topic must match the topic you set in your Domain App handler.
      topics: ["office"],
    });

    const voiceClient = client.voice;

    await voiceClient.listen({
      topics: ["office"],
      onCallReceived: async (call) => {
        console.log("Call received:", call.id, call.from, call.to);

        try {
          await call.answer();
          console.log("Inbound call answered");
          await call.playTTS({ text: "Welcome to SignalWire!" });
        } catch (error) {
          console.error("Error answering inbound call", error);
        }
      },
    });
    ```
  </Tab>

  <Tab title="RELAY V3">
    ```js
    import { Voice } from "@signalwire/realtime-api";

    const client = new Voice.Client({
      project: "your-project-id",
      token: "your-api-token",
      // This context must match the context you set in your Domain App handler.
      contexts: ["office"],
    });

    client.on("call.received", async (call) => {
      console.log("Call received:", call.id, call.from, call.to);

      try {
        await call.answer();
        console.log("Inbound call answered");
        const playback = await call.playTTS({ text: "Welcome to SignalWire!" });
        await playback.ended();
      } catch (error) {
        console.error("Error answering inbound call", error);
      }
    });
    ```
  </Tab>
</Tabs>

Find the many options for what you can do with RELAY in our [RELAY Realtime SDK reference](/docs/server-sdk/node).

## Video Room

You can immediately connect inbound SIP calls to a video room. To use the **Video Room handler**, search for the video room name in the settings dropdown and select the video room you would like to use. Inbound calls will be automatically directed to this video room.

<Tip>
  For a full guide to creating and configuring new Domain Applications, visit our [SIP Space help page](/docs/platform/your-signalwire-api-space).
</Tip>