Monday, July 2, 2007

iPhone Telephone Hyperlinks


Enough with the iPhone news. Let’s talk about a little detail that no one else is talking about. The interesting thing for me is how the web is joining our good friend the telephone. A while back I talked about Callto links and how these could be tied into Vonage using a little click-to-call tool I wrote. So I was pretty interested to see how the iPhone would allow a web-page to connect to a telephone number.

I was expecting either callto: links or perhaps a telephone microformat or perhaps a proprietary solution.

Surprisingly it turns out that it’s none of the above. The iPhone is using a not so well known RFC to create click-to-call HTML telephone hyperlinks. This is done through a tel: link format that I’d never heard of called RFC 3966.

The format allows you to create an anchor link and use a tel: URI to point to a telephone number.
For example, if you wanted to contact Apple customer support you would use a link like this:

Call Apple Customer Support at 1-800-275-2273

Go ahead and give it a try, I don’t yet have an iPhone to test this out.

The link format is fairly straightforward:



 If more sites start using this for their contact information, other providers for the tel: URI may begin supporting the format (Vonage, Verizon, Skype, etc.) This makes it easy to transition from a web interface to a voice interface. The format also theoretically supports alternative SIP providers and extensions, making it possible to put a corporate directory online in the form of an iPhone application.

Update: Apple also supports turning off auto-detection of phone numbers via a meta-tag.

Update 2:  When I first wrote this post we hadn’t done any real iPhone work. I didn’t even own an iPhone. Since then a lot has changed, our company now focuses on building world-class apps. Learn more from our homepage and let me know if we can help.


Do you have a project in mind? We’d love to work with you. If you’d like an opportunity to work on projects with us, check out our Careers page. We’re hiring!