href=tel in anchor code example
Example 1: href phone
<a href="tel:+5511981724236">98172-4236</a>
Example 2: html telephone
<a href="tel:0612345678">Call me!</a>
<a href="tel:+5511981724236">98172-4236</a>
<a href="tel:0612345678">Call me!</a>