How do I include extensions in the tel: URI?

Question

I currently have a webpage serving up phone numbers, some of these phone numbers have extensions so I have written the HTML like this:

Answer 1

In all the examples I saw, the value of ext is contained in the full number. So try including 88 in the href value:

<a href="tel:+44-1234-56788;ext=88">+44-1234-56788</a>