Thanks for your reply. So for your SIII mini for example, is it just the 9 phone fields I mentioned from the I9000? Or does it have more like the 21 phone fields the generic Android version has? You can find out by creating a new contact and clicking the label button next to the phone field.
As far as I know the 'generic android' contacts app seems like a 'default' android app, and not a third party kinda thing.
You're right - I could add them as custom fields, but I'm developing an app to transfer contacts, so I need to know anyway.