Go to desk.zoho.com.

You will see your account as shown in the screenshot. 

Click on it and you will see a new menu.

You will notice the phone option to call, you most likely will be offline. Click on it and change it to online. 

Once you are online the bottom will be green.

Go to the ticket of the contact information of the student you need to call.  

You will see the phone number of the person you need to contact and the icon of a phone will light up green once you are online.

Click on the icon and the call will be placed. 

A notification will appear for you to allow using the audio on your device, click allow and the phone will start ringing.

Once you are done with the call, click on End Call.

A ticket will be created indicating a call has been made. Click on Close.

If they don’t answer, leave a voicemail message and follow the same instructions. A ticket will be created and the Status will be Open. After leaving a voicemail, click Close.