To display html tags in html format we have to use different ways. You can convert your html code in html special Characters to show tags into you Page. After convert special Characters you use <pre>. The <pre> tag is quite useful for displaying organized code. Otherwise your html code display in one line.
Where +91 is country code 0123456780 is demo number, You can replace this from your original number. Below is a clickable phone link you can test. In non-phone browsers (PC and Mac desktop and laptop computers), this link may be open Skype, ask you for the application to use, may give the user an error, or nothing will happen.