iClosed currently doesn't have an integrated dialer, simply because customers already use various phone dialers as Chrome extensions. Here's how it works.
Navigate to Chrome Web Store and install click-to-call dialer at your preference. All you need is an app, that you may have already, that has a Chrome extension dialer that will recognize phone numbers on a web page. Check out videos below:
Making phone calls from 
AI Scheduler pages
Making phone calls from 
Global Data
Pro tips
Even though Chrome extensions will add additional useful functionalities in your browser, kindly note that they may also slow down your browsing experience.
In case your iClosed pages are loading slower than usual, Chrome extension may be the reason. Look into all Chrome extensions that you have installed, and turn them off to keep your browsing faster and fully optimized.