# Control an Incompatible IP Phone by Cloud Voice App Desktop Client

CTI (Computer Telephony Integration) mode lets you pair a desk phone with the Cloud Voice App desktop client even when the phone itself is not on the CTI-compatible list. An IP phone (Internet Protocol phone: a desk phone that connects over your network) registered to your extension links to the app, and the app becomes an on-screen control panel. You dial, answer, and manage calls from the desktop client, while the audio (talking and listening) stays on the physical phone.

Use this when a technician or user prefers the comfort of a handset for audio but wants the point-and-click convenience of the app for handling calls.

## When to use this

Follow these steps only for IP phones that are not among the CTI-compatible models. If your phone is on the supported list, it works with CTI directly and no extra setup is needed.

To confirm whether your model qualifies for native CTI support, check the compatible Yealink, Fanvil, Snom, and Grandstream devices in the [CTI overview](/pbx/desktop-client-user-guide/cloud-voice-app-desktop-client-cti-overview/).

:::note
This page is specifically for phones that fall outside the compatible-device lists. A supported phone does not need CTI mode enabled by hand: it connects on its own.
:::

## Before you begin

Confirm that the IP phone is registered with the same extension that you use to sign in to the Cloud Voice App desktop client.

:::caution
The extension on the phone and the extension on the desktop client must match exactly. CTI mode can only bind the two together when they share one extension. If they differ, the phone will not appear in the drop-down list in the next step.
:::

## Switch the desktop client to CTI mode

1. Sign in to the Cloud Voice App desktop client.
2. In the top-right corner, click the CTI icon ![CTI mode toggle](/images/pbx/cti.png).
3. Choose your connected IP phone from the drop-down list.

![Selecting a connected IP phone to enable CTI mode in the desktop client](/images/pbx/non-compatible--cti-mode-desktop.png)

:::tip
Only phones registered to your extension show up in the drop-down. If the phone you expect is missing, recheck its registration and its extension before troubleshooting anything else.
:::

## What you can control

With the phone linked, you can run these call actions from the desktop client while the audio runs on the IP phone:

- Place and end calls
- Reject an incoming call
- Hold and resume a call
- Blind transfer a call (send the call to another number without speaking to that person first)
- Record a call