Hi
Only the calls or messages sent through AT&T will show on your history, so if you use some sort of a third party calling or texting app, no records will be saved (usually those work only with the same app users). as far as the 0 number, I believe it usually meant the number is unavailable or blocked, so while delivered, AT&T doesn't have a record of it as it was hidden on the originating end.
Thanks,
Dmitriy