Updates: It seems like google started showing the phone numbers listed in google business page for the location extension enabled campaign. It means, from now based on the location google will show the phone number listed from your google my business listing.
So it is time to update our call extension and also update the google my business listing phone number field.
In future, google seems to be in plan to automatically show the phone numbers from the landing page. So looking forward for this “Automated call extension” similarly like “Automated sitelink extension”.