When running in a browser on a mobile phone, <meta name="format-detection"/> determines whether or not telephone numbers in the HTML content will appear as hypertext links. The user can click a link with a telephone number to initiate a phone call to that phone number.

<meta name="format-detection" content="telephone=yes"/> (default on Safari in iOS)

content="telephone=yes" indicates that telephone numbers in the HTML code should appear as hypertext links that can be clicked to make a phone call.

<meta name="format-detection" content="telephone=no"/>

content="telephone=no" indicates that telephone numbers in the HTML code should not appear as hypertext links.