Telephone Numbers on Smart Phones Last Updated February 2021 To make a telephone number clickable on a smart phone you simply need to add a little HTML code. Example: <a href=“tel:+15122322576“>512-232-2576</a> or <a href=“tel:+15122322576“>Click to Call the Web Team!</a> Note the syntax is similar to email addresses: <a href=”mailto:cofawebmaster@austin.utexas.edu”>cofawebmaster@austin.utexas.edu</a> mailto: and tel: are both protocols. Learn More CSS Tricks goes into extensive detail in the article, The Current State of Telephone Links.