---
title: Connect PBX
excerpt: Connect your PBX (3CX) to CX-Engine for screen pop and call logging on inbound and outbound calls.
order: 3
---

## Authentication Types

CX-Engine supports two OAuth 2.0 methods for authenticating your PBX connection:

| Method | Description |
|---|---|
| **Authorization Code** | The PBX redirects a user to CX-Engine to approve the connection interactively. This is the method used by the standard CRM template. |
| **Client Credentials** | Server-to-server authentication using only a client ID and secret. No user interaction or redirect required. |

> **The password grant is not supported** for PBX integrations. Only Authorization Code and Client Credentials are available.

Use **Authorization Code** when using the standard XML template (the method described below). Use **Client Credentials** for automated or headless setups where no browser redirect is possible.

---

## Connecting 3CX

### Create an OAuth 2.0 Client

In the CX-Engine application, go to the **API Clients** menu and click **Add Client**.

![Add an OAuth client](/images/docs/middleware-crm/image-add-oauth-client.png)

Keep note of the `Client ID` and `Client Secret` values — you will need to enter them in 3CX.

### Import the CRM Template

From the advanced connector configuration page at **CRM Connector** > **Settings**, click the **Download XML Template** button in the top-right corner of the screen, then select your PBX system and submit.

The filename to be uploaded must not contain spaces or special characters. We recommend keeping the original filename: `CXEngine.xml`.

Once the CRM template file is on your machine, go to your 3CX instance under **Admin** > **Integrations** > **CRM**.

Upload the file using the **Add Template** button. Once the template is imported and selected, fill in the following values:

- **Client ID**: the Client ID previously generated in the CX-Engine interface
- **Client Secret**: the Client Secret previously generated in the CX-Engine interface
- **Account ID**: the CX-Engine client ID as shown in the interface, under the **Clients** section

Save the settings, then click **Authorize** to authorize the connection in the CX-Engine interface:

![Authorize the connection in the CX-Engine interface](/images/docs/middleware-crm/image-oauth-authorize-cx-engine.png)

After clicking **Authorize**, you will be automatically redirected to 3CX:

![Authorize the connection in the 3CX interface](/images/docs/middleware-crm/image-oauth-authorize-3cx.png)

You can close this window and reload the integrations page in 3CX. Make sure to check the **Enable call logging** checkbox if applicable.

![Integration configuration in 3CX](/images/docs/middleware-crm/image-integration-3cx-page.png)

> **Important**: If you run tests from this page using the test button, remember to click **Authorize** again to refresh the token before leaving the page. Otherwise, subsequent calls will not work (3CX does not save the fresh token after a test from this interface).