Hacker News Reader

Worldwide 10 digit format? News to me. Can you say more?

There was a campaign that went something like "de hele wereld bellen, even tot tien bellen"

I think I'm wrong, it was about the 10-digit Dutch numbers.

Probably UPT[0].

Has it been implemented by any carriers?

The US phone system had such a service for a few years (area code 500 iirc). It had so little uptake that it was shut down.