Go to and make sure that your desk phone's selected. If you see My Computer instead of your desk phone, select it and switch to your desk phone.
Dial a number from your app or make a Webex call, and your call goes through your phone. Pick up your handset, use your headset, or talk over your speakerphone on your phone. Then, if you're set up with Calling in Webex (Unified CM or Webex Calling), you can continue controlling your phone from the app to put calls on hold and merge and transfer them too. You'll see everything taking place on the phone display.
Webex | Make Calls with Your Desk Phone
When you're connected to your desk phone from Webex, you can dial a number or make a call in Webex and your call goes through your phone. Webex acts like a remote control for your phone so you don't need to shift your focus away from your computer when you want to make a call.