How to a get Microsoft Teams to launch when I click on a telephone number.

“We want customers to be able to click on our telephone number on the support web page, and have Microsoft Teams dial the number.”

Three ways to do it, not supported in all browsers unfortunately:

tel:
<a href=”tel:1800 020 140″>555-1212</a> 555-1212

callto:
<a href=”callto:1800 020 140″>555-1212</a>

skype:
<a href=”skype:1800 020 140″>555-1212</a>

tel: has a RFC (proposed) standard explaining it’s use – RFC5341 – IANA Registry for TEL URI Parameters
(by default, tel: is the only one linkable by WordPress)