If there was a trivial way to let mobile phone users call you from your web site, just by adding a single HTML element to the page, would you do it?
In fact, there is. It doesn't even require a mobile WebRTC browser. It works for virtually any smartphone and a growing number of desktops too.
The tel: URI is defined in RFC 3966.
For most mobile phone users, if they click a link to a tel: URI, their browser will copy the link into their dialer for convenience.
To protect users against calls to 0900 premium rate numbers, the user still has to make one more click to confirm they want to dial.
Here is a tel: URI:
Here is how to create a link with it:
<a href="tel:+44-20-7135-7070">020 7135 7070 (from abroad: +44 20 7135 7070)</a>
and here is how it looks on the page:
(Note: some planet aggregation sites block the link in the example)
and here is what appears on the mobile device after a user clicks the tel: URI link:
Many desktop users can also benefit from tel: URIs. If they have a modern telephone system in their office, the system administrator may have already added a tel: URI handler to their desktop.
Anyone with a software PBX or a SIP account can also potentially use the TBDialOut extension for Thunderbird to help convert address book phone numbers into tel: or sip: URIs or even URLs for some bespoke dialer.
For those who want extra convenience, the Telify extension for Firefox will look for phone numbers in any HTML page and display them as tel: URIs so you can click them even if the web developer overlooked this.