> There is also another concern - do you want to make sure phone numbers are > not shared?
Michal,
Shared with whom? I run a solo professional services consultancy so there's only me here the database.
Multiple contacts at the same client company. If, for whatever reason, the phone number changes you've got to update X rows in your contacts table, whereas only one row needs to be updated when the schema meets 1NF. This eliminates update anomalies.