URL Scheme for Phone Call

Solution 1:

The official standard for providing a telephone number as a URI is here: http://www.ietf.org/rfc/rfc3966.txt

It basically says use tel: as the prefix, and start the number with +[international dialling code] before the number itself. You can put non-numeric characters as separators (e.g. -) but they must be ignored. So a London (UK) number might be:

tel:+44-20-8123-4567

A New York (US) number:

tel:+1-212-555-1234

Solution 2:

There is such a URI scheme: tel. It has an elaborate syntax, but here is a simple example of its usage:

tel:123-4567

For the full specification, refer to http://www.ietf.org/rfc/rfc3966.txt .