tel: and sms: links in HTML: syntax, extensions and iPhone vs Android differences

tel: and sms: links turn a phone number into a one-tap action. They are simple, but they have compatibility details worth knowing.

Published on October 6, 2026 · By the QLinky team

Call link

<a href="tel:+13051234567">Call (305) 123-4567</a>

• The href takes the number in international format, with + and the country code. That way it works even if the person is in another country.
• The visible text can use the local format your audience recognizes.
• Inside the href, hyphens are allowed as separators (tel:+52-998-123-4567), but spaces are not.

Extensions and pauses

To dial an extension after the switchboard answers, add one comma for each pause of about two seconds and then the extension:

<a href="tel:+525512345678,,123">Call sales (ext. 123)</a>

The standard also defines the ;ext=123 form, but commas are what works best in phone dialers.

Link to send an SMS

<a href="sms:+13051234567?&body=Hi%2C%20I%27d%20like%20some%20information">Send SMS</a>

The historical difference between systems is in how the number is separated from the message:

The ?&body= combination is the one QLinky uses because it works on both. Even so, test the link on both systems if you can: the behavior also depends on the messaging app installed.

What happens on a computer

A tel: link on a computer opens whichever application is registered for calls: FaceTime on a Mac, or video calling and phone-link programs on Windows. If there is none, nothing happens. The same goes for sms:.

That is why it's a good idea to always show the number as text, and not just an icon.

Good practices

• Say what will happen. “Call now” is clearer than a bare number.
• Large tap area. On a phone, a button at least 44 pixels tall avoids missed taps.
• Opening hours in view. If you only answer during certain hours, put them next to the button.
• Automatic detection. Phones often turn anything that looks like a phone number into a link. If it converts numbers that aren't (product codes, for example), on iPhone you can turn it off with <meta name="format-detection" content="telephone=no"> and link the real numbers by hand.
• Social networks: most profiles only accept http or https links, so tel: and sms: don't work there.