The Click-to-Call functionality is supported with the new Outlook version. It isn't available in Classic Outlook. We recommend to switch to New Outlook, which includes click-to-call functionality.
You can find the "Try the new Outlook" switch (or similar) in the upper-right corner of the main toolbar of the Outlook window.
Once clicked, Outlook may prompt to confirm; select "Switch to New Outlook."
Following contact selection, clients can initiate a Ringotel call by clicking the "call" button or tapping the displayed number. The call will begin automatically.