1. During the Zoiper installation choose the "Install Click2Dial" check box.
2. Open your Internet Explorer browser.
3. You will see a pop-up on the bottom, asking you to either "Enable" or "Don't enable" the Zoiper Click2Dial plugin. Choose "Enable".
4. You can additionally check if the Click2Dial plugin is enabled by, by going through Settings > Manage add-ons:
5. A pop-up window will be shown where you can see if the Click2Dial plugin is enabled. It should be under Add-on Types > Toolbars and Extensions:
6. After the restart of Internet Explorer, you should already see the Click2Dial plugin in action, as such: