<meta name="format-detection">
Stops Safari from turning every phone-looking number into a blue link.
iOS Safari scans the page for sequences that look like phone numbers and converts them into dialing links — blue underline included, on top of your CSS. telephone=no turns the guessing off for the whole document.
Outside the specification, an Apple extension, and still indispensable on pages full of serial numbers, tracking codes and IDs that merely look like phones. To make a number clickable on purpose, the honest path remains href="tel:…".
<meta name="format-detection" content="telephone=no">