Now when browsing on mobile devices that have the ability to make calls, people can click on phone numbers in web pages or HTML emails, or links in native apps and their device will make a call. The same is true for some desktop web browsers that can access VOIP applications such as Skype. The issue here is that all devices don’t always call the correct number, and international codes sometimes don’t work.
Use the tel URI scheme:
Native iOS application URL string: