# Control a Yealink IP Phone from the Cloud Voice App Web Client

When you put the Cloud Voice App Web Client into CTI mode, it pairs with a Yealink IP phone that is registered to your extension. CTI stands for Computer Telephony Integration, a way to drive a desk phone from your computer. Calls are still dialed and answered on the Yealink handset itself, but you run each one from the web client, which becomes a visual control panel for the phone.

## Where this applies

Follow these steps for the [Yealink models that support Cloud Voice App Web Client CTI](/pbx/web-client-user-guide/cloud-voice-app-web-client-cti-overview/#linkus-web-client-cti__compatible-yealink).

:::tip
If your phone isn't on the compatible list, use [Control an Incompatible IP Phone from the Cloud Voice App Web Client](/pbx/web-client-user-guide/remotely-control-an-incompatible-ip-phone-by-cloud-voice-app-web-client/) instead.
:::

## Before you begin

Confirm the following, which your system administrator manages on the phone system:

- The **uaCSTA** feature is turned on, under **PBX Settings > SIP Settings > Advanced > Other Options > Enable uaCSTA Connection**.

:::note
uaCSTA (user-agent Computer Supported Telecommunications Applications) is the signaling channel that carries your control commands from the web client to the phone. Without it, CTI mode has no way to reach the handset.
:::

On the handset, the Yealink phone must be registered with the same extension you sign in with on the Cloud Voice App Web Client.

:::caution
Register only one account on the Yealink phone. Adding more than one can prevent CTI from working.
:::

## Step 1: Make the Yealink phone controllable

:::note
If your administrator assigned your extension to the phone through Auto Provisioning, the handset is already ready to be controlled. Go straight to [Step 2](#step-2-turn-on-cti-mode-in-the-web-client).
:::

If your extension was registered on the phone by hand instead, enable the CSTA control feature first. CSTA Control is the phone-side switch that lets the handset accept the uaCSTA commands from the web client. The steps below use a Yealink T56A as the example.

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

   ![Yealink Remote Control page with the CSTA Control option enabled](/images/pbx/yealink-csta-control.png)
4. Click **Confirm**.
5. When the confirmation dialog appears, click **OK** to reboot the phone.

   :::caution
   Rebooting takes the phone offline for a minute or so, and any call in progress will drop. Do this when the phone is idle, or warn the user first.
   :::

## Step 2: Turn on CTI mode in the web client

Putting the web client into CTI mode is what lets you manage the calls taking place on your Yealink phone.

1. Sign in to the Cloud Voice App Web 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 drop-down list.

   ![Drop-down list for selecting a connected Yealink phone to control in CTI mode](/images/pbx/yealink-cti-mode.png)

## What you can control

With the Yealink phone linked, the web client lets you handle its calls in these ways:

- 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 a call
- Swap between held calls
- Flip a call