Der Trick beruht auf folgendem Artikel : https://css-tricks.com/the-current-state-of-telephone-links/
/* https://css-tricks.com/the-current-state-of-telephone-links/ */
a[href^="tel:"] {
color: orange;
text-decoration: none;
}
a[href^="tel:"]:before {
content: "\260e";
margin-right: 0.5em;
}