# Control a Yealink IP Phone with the Cloud Voice App

CTI (Computer Telephony Integration) mode links a Yealink IP phone that carries your extension to the Cloud Voice App desktop client. Once the two are paired, the desktop app becomes an on-screen control panel for your calls: you dial, answer, transfer, and hang up from the app, while the audio and the actual call handling stay on the Yealink phone.

## Where this applies

Use these steps with any Yealink handset that supports CTI in the Cloud Voice App desktop client. For the full compatibility list, see the [CTI overview](/pbx/desktop-client-user-guide/cloud-voice-app-desktop-client-cti-overview/#linkus-web-client-cti__table_v1t_krr_zbc).

:::tip
Using a phone that isn't on the compatible list? Follow [Control an Incompatible IP Phone with the Cloud Voice App](/pbx/desktop-client-user-guide/remotely-control-an-incompatible-ip-phone-by-cloud-voice-app-desktop-client/) instead.
:::

## Before you start

Two things must be in place before CTI mode will connect:

- **On the PBX**: The uaCSTA feature must be turned on. (uaCSTA is the SIP-based protocol that lets the app relay control commands to the phone.) Your administrator enables it under **PBX Settings > SIP Settings > Advanced > Other Options > Enable uaCSTA Connection**.
- **On the IP phone**: The phone must be registered with the same extension you use in the Cloud Voice App desktop client.

:::caution
Register only one account on the IP phone. Additional accounts can stop CTI from working.
:::

## Step 1. Make the IP phone controllable

:::note
If your administrator pushed your extension to the phone through Auto Provisioning, the phone is already set up for control. Skip ahead to Step 2.
:::

If your extension was registered on the phone by hand, switch on the phone's CSTA Control before pairing. (CSTA Control is the handset side of the uaCSTA feature: both the PBX and the phone must have it on.) The steps below use a Yealink T56A as the example:

1. Sign in to the phone's web interface.
2. Open **Features > Remote Control**.
3. On the **Remote Control** page, enable **CSTA Control**.

   ![Remote Control page with the CSTA Control toggle switched on](/images/pbx/yealink-csta-control.png)

4. Click **Confirm**.
5. When prompted, click **OK** to reboot the phone.

:::caution
The phone restarts to apply the change. Any call in progress on that handset drops, and the extension is offline for the length of the reboot. Do this when the phone is idle.
:::

## Step 2. Turn on CTI mode in the desktop app

Switching the desktop app into CTI mode is what lets it manage calls on your IP phone.

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

   ![Selecting a paired Yealink phone from the CTI mode menu in the desktop app](/images/pbx/yealink-cti-mode-desktop.png)

## What you can do

With the phone paired, you can run these call actions from the Cloud Voice App while the Yealink phone carries the call:

- Place and end a call
- Start a second call
- Answer or reject an incoming call
- Record a call
- Transfer a call, both attended and blind
- Hold and resume
- Swap between held calls
- Flip a call