# WebRTC Trunk Overview

A WebRTC trunk gives your customers a way to reach your phone system directly from their web browser. Rather than routing calls over a conventional SIP (Session Initiation Protocol) trunk, it relies on WebRTC (Web Real-Time Communication) to carry live audio and video inside a web page.

When you publish a WebRTC trunk, Cloud Voice generates a call link. A customer simply clicks that link to connect to your business at no charge to them, with nothing to download and no browser plug-ins to install. A call that starts as audio can also be promoted to video mid-conversation, so agents and callers can move to a face-to-face exchange whenever it helps the interaction.

:::note
A WebRTC trunk is aimed at your customers, not your staff. The person clicking the link does not need a Cloud Voice account, the Cloud Voice App, or any login. They just need a supported browser (see below). Use it when you want a "click to call us" button on a website or in an email.
:::

## What you need

Before you set up a WebRTC trunk, confirm the following:

- **Subscription plan**: Video calling requires the **Ultimate Plan**. Audio-only WebRTC calls do not.
- **System version**: Your Cloud Voice system must be running firmware **84.11.0.22** or later.

:::caution
Video is the part that depends on the plan. On any lower plan the trunk still works for audio, but callers will not be able to switch to video. If a customer expects face-to-face calling, verify the account is on the Ultimate Plan first.
:::

:::caution
The WebRTC trunk option only appears once the system is on firmware **84.11.0.22** or later. If you cannot find the feature, check the firmware version before troubleshooting anything else.
:::

## Limits

Keep these ceilings in mind when planning how you will use WebRTC trunks:

- You can create a maximum of **5** WebRTC trunks.
- Each WebRTC trunk handles up to **10** simultaneous (concurrent) calls.

:::caution
The limit of 10 is per trunk and counts calls that are active at the same moment. When all 10 slots on a trunk are in use, the next caller cannot connect until one of the calls ends. If you expect more than 10 people on calls at once, spread the load across additional trunks (up to the maximum of 5).
:::

## Supported browsers

Customers can place WebRTC calls from any of the browsers listed below. Earlier releases are not supported.

| Browser | Minimum version |
| --- | --- |
| Google Chrome | Chrome 87 or later |
| Microsoft Edge | Edge 87 or later |
| Opera | Opera 72 or later |

:::tip
The call link runs entirely in the browser, so a caller who reports that the link does nothing is usually on an unsupported or outdated browser. Asking them to update to a current version of Chrome, Edge, or Opera resolves most connection problems.
:::