Geek alert … tel: or callto:?

! This post hasn't been updated in over a year. A lot can change in a year including my opinion and the amount of naughty words I use. There's a good chance that there's something in what's written below that someone will find objectionable. That's fine, if I tried to please everybody all of the time then I'd be a Lib Dem (remember them?) and I'm certainly not one of those. The point is, I'm not the kind of person to try and alter history in case I said something in the past that someone can use against me in the future but just remember that the person I was then isn't the person I am now nor the person I'll be in a year's time.

Time for another geek interlude – tel: versus callto:

Taking WAP out of the equation because it’s so old as to be irrelevant, there are two ways to mark up telephone numbers in HTML.  The tel: URI (Universal Resource Indicator – it tells your browser what it can expect to find at the destination of your link) is the official standard for marking up telephone numbers whilst callto: is a proprietary URI made popular by Skype and unsurprisingly, Microsoft.

By marking up a telephone number, it makes it easier for visitors to your website to make phone calls from their phones or computers – click on the link and it launches whichever application is set up to handle phone calls.  But the problem is, which of the two do you accommodate on your website?  Mobile devices are the obvious target because they’re usually going to be mobile phones so tel: would seem to be the obvious choice but it’s not uncommon for people to have Skype phones or another VoIP phone service so callto: support would be useful.

But you can’t have both so which should you use?  Do you encourage standards compliance by using tel: or pander to the embrace and extend ethos of Sky and Microsoft and use callto:?  Do you cater for mobile devices with tel: or desktops with callto:?

With the rapid convergence of internet and phones, we need some standards compliance in the major browsers.  The last thing we need is a VHS/Betamax or Blueray/HD-DVD battle over telephone number markup standards!


  1. Daggs (55 comments) says:


  2. revinkevin (176 comments) says:

    I’d guess for phone numbers use tell tag and for voip numbers use the callto tag.

    I’ve not seen those tags myself.

  3. axel (1214 comments) says:

    ‘callto’, if i see a number I dial it, with my phone, the only people who will have the head phone mic set up will be Skypers and they will zap the link!

    why cant you have both?

  4. axel (1214 comments) says:

    i remember a similair thing with ‘mailto’ and what ever the crappy old version of it was, about 10 15 years ago

  5. axel (1214 comments) says:

    good game, good game, i seriously hope we dont get the miracle they are talking about, the only thing worse than england in the final stages, is scotland in the finals, i really hate how sporting events seeem to take over the media

  6. axel (1214 comments) says:

    What ‘new things’ has the Human Rights Act, given us?

    I always thought we were a ‘nice country’ and didn’t really need it?

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