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

# Web Calls

> Let visitors talk to your AI agent from the browser - no phone number dialled, no carrier involved.

Web calls let a visitor speak to your AI agent **directly from a web page**, using their microphone. Same agent, same prompt, same tools and booking - but the audio travels over the internet instead of a phone line. No carrier minutes are used, and it works from any country with zero telephony setup.

<Info>
  A web call **is** an inbound call to the number's agent. It appears in call history, is recorded, analysed, billed, and fires webhooks exactly like a phone call. The caller shows as `web`.
</Info>

## Enabling web calls on a number

Web calls are **off by default** on every number. Turn them on per number:

```bash theme={null}
curl -X PUT https://api.nixflex.com/v1/integrations/web-calls/number/+441234567890 \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"enabled": true}'
```

`GET` the same path to read the flag, `DELETE` to force it off. Turning the flag off is the kill switch - every start request for that number is refused from that moment.

## Pricing

Calls on a number with web calls enabled bill at \*\*$0.09 per minute** - the same rate as [Live Monitor](/concepts/live-monitor). The two switches are independent, but the price is one rule: **either** feature enabled on a number means that number's calls bill at $0.09/min. Both enabled is still \$0.09 - never more.

Web calls use no carrier, so there are no Twilio/Telnyx charges at all on these calls.

## Starting a call from your own page

The start endpoint is public - the **number is the identity**. No API key ever reaches the browser; the engine verifies the flag, the owner's balance, the agent, and concurrency on every single request.

```bash theme={null}
POST https://api.nixflex.com/web-call/start
Content-Type: application/json

{"number": "+441234567890"}
```

Success returns the visitor's audio credentials:

```json theme={null}
{
  "ok": true,
  "call_id": "WEB...",
  "livekit": { "url": "wss://...", "token": "...", "room": "webcall-WEB..." }
}
```

Join with [livekit-client](https://www.npmjs.com/package/livekit-client), publish the microphone, and the agent answers:

```js theme={null}
const room = new LivekitClient.Room();
await room.connect(res.livekit.url, res.livekit.token);
room.on(LivekitClient.RoomEvent.TrackSubscribed, (track) => {
  if (track.kind === 'audio') document.body.appendChild(track.attach());
});
await room.localParticipant.setMicrophoneEnabled(true);
```

<Tip>
  Ask for microphone permission **before** calling the start endpoint. If you start the call first, the agent greets while your visitor is still looking at the permission popup.
</Tip>

A refused start returns `{"ok": false, "reason": "..."}` - `unavailable` (number unknown, feature off, or owner unfunded), `busy` (concurrency cap), or `bad_number`.

## Behaviour and guarantees

* **Inbound only.** A web call always rings *in* to the number's agent.
* **Everything is inherited.** Voice, prompt, language, booking tools, custom functions, transfers, webhooks, post-call analysis - whatever the number's agent does on the phone, it does on the web.
* **Interruptions work.** Visitors can talk over the agent and it stops, like a phone call.
* **Recording included.** If recording is on for the number/agent, web calls are recorded - and an interrupted sentence is recorded only up to the moment it was cut, exactly as the visitor heard it.
* **Caller identity is `web`.** Every visitor arrives as the same caller, so caller history and greet-by-name are deliberately skipped on web calls.
* **No SMS destination.** A browser visitor has no phone number, so `[SEND_SMS]` and booking confirmation texts cannot be delivered. Tell your agent in its prompt not to offer texts on web calls - or have it collect a mobile number first.

## Related

* [Web Agent widget](/web-assistant/overview) - the embeddable Call + Chat launcher
* [Live Monitor](/concepts/live-monitor) - listen to calls live at the same \$0.09 rate