The problem with fictitious numbers is that they normally don't look invalid. I don't want to supply them with a contact number which merely doesn't work; I wan

The problem with fictitious numbers is that they normally don't look invalid. I don't want to supply them with a contact number which merely doesn't work; I want to supply them with a contact number which is obviously not a real number at a glance. Hence why I use 0 where possible. Ideally I'd prefer them to allow me to leave the number blank, of course.