Install the Webex Calling S4B App
If you want to continue using the Microsoft Skype for Business app to collaborate with your team but also want to be able to make and receive calls from outside your organization, install the Webex Calling S4B app. The Webex Calling S4B app is automatically integrated with your Microsoft Skype app so that when you make a call from your Microsoft Skype app, the Webex Calling S4B app opens and completes the call. You can then make use of all the calling features the Webex Calling S4B app has to offer.
After you install the Webex Calling S4B app, the app is minimized and can be found in the Windows SysTray, to the right of your Taskbar.
Sign in to https://settings.webex.com, click Download Webex Calling.
You're then brought to the Calling User Portal My Apps page.
Download the Webex Calling Desktop App with S4B Integration.
The app is only available on Windows.
Click Run or Save and then follow the instructions
Select your region and then sign into the app to start making calls.
If you enter an incorrect region, you can always change it by going to Options
and then Edit Login Info.