Select Phone Service under Settings. The settings menu can be found under "Edit profile" after clicking on your initials or profile picture in the top-left of Webex.
Enter your Username and Password and click "Sign in".
Once you are successfully signed in, there will be 2 green checks next to Phone Service and Voicemail Service. You should now be able to place and receive phone calls and voicemails in Webex. Please note that, if you are working remotely, you must have Webex installed locally on your computer rather than in the cloud. You can download and install Webex on a Windows PC by going to webex.com/downloads and clicking the "For Windows (64 bit)" button.
If the application is not connected to your desk phone or if you do not have a soft phone configured, there will be a red X next to Phone Service. If, after restarting Webex and signing into phone services again, you still see a red X rather than a green check mark, please submit a service request under Services -> Communication and Collaboration -> Conferencing and Telephones -> Webex.