Which Internet telephony protocol has the widest support?

Question

I am looking for a better way to initiate a call from a web page and am trying to choose between the callto: protocol and tel: URL protocol.

The link will be a regular phone number, not a Skype account, and I try to support as many platforms as possible, including Skype and other similar VOIP applications, as well as smartphones such as the iPhone.

Examples of such tags are welcome!

Answer 1

SIP is the most widely used VoIP protocol. If you search for "SIP Provider" or browse the list of networks on SIP Broker , you will get an idea of ​​its prevalence. Although in his wisdom, Skype decided to restrict SIP access to its network.

The SIP standard actually defines a URI of the form sip: [e-mail] or sips: [e-mail]. If your browser plug-in supports SIP URI, this will be a good start.

Answer 2

A quick look at the wikipedia uri scheme (http://en.wikipedia.org/wiki/URI_scheme) shows that tel: and sip: are official uri schemes, contrary to callto: this is an unofficial skype scheme. Then I recommend using tel: or sip :. Be wise when using this, because browsers can have unpredictable behavior, IE 6, for example, will try to follow the link and open a blank error page.