Markus Ernst wrote:
So, while e-mail addresses have a strictly defined format, this does not apply to phone numbers. Internationalisation would be necessary to validate them, and still it would be a hard task, as complete sets of valid formats might not be available for every country.
FWIW I would imagine that the most useful aspect of <input type="tel"> or whatever would not be validation (because validation is hard) but would be better integration on mobile devices e.g. making the default action of the keypad be number keys, making phone numbers from the contacts list available, etc. (these were both pointed out already). Therefore whilst I totally recommend this feature be postponed for HTML6, I think it makes a lot of sense and that problems with validation are a red herring.
