The link type <a href="tel:nnnnnnnn">nn nnnn nnnn</a> which works in e.g. Text and Media, Page HTML has the href component stripped in forum posts, i.e.

 <a href="tel:nnnnnnnn">nn nnnn nnnn</a>

becomes

<a>nn nnnn nnnn</a>

To recreate:

Create a Text and Media activity.

• Create a link to a telephone number, either via the HTML pane or using the link icon in the WYSIWYG pane. <a href="tel:61312345678">+61 3 12345678</a>
• Save and view the result.
• Note that the phone number is clickable in the browser on desktop, and on a mobile device will trigger a prompt to call the number.

Create a forum post and follow the same procedure to create the link.

• After saving, note that the HTML has had the href component stripped. The phone number is not clickable on either desktop or mobile.
• Viewing the HTML, <a href="tel:61312345678">+61 3 12345678</a> has been changed to <a>+61 3 12345678</a>

Expected behaviour is that the forum post link should behave the same as a T&M link.

Note that the tel: link works in the forum description.

This was discovered in 4.1.6 but I'm not in a position to initiate an upgrade to a more recent version. I started up a new test site in 4.4.2 and was able to recreate the same issue.