If Stephen can be pronounced like Steven, then Stephanie should be pronounced "Steev-en-ee".
-- Anonymous User 2/20/2008
The secret is in the length of the first e. In Greek, the ph combination makes an f sound, as in telephone, Phoebe etc. But when the first syllable of Stephen has a long eee sound, this affects the f and it becomes a v; not in spelling originally, but in sound. English-speaking people have for centuries found this easier to pronounce.
In German, the first e is a short sound, and they spell and say the name: STEFF-an. (SHTEFF-an, actually.) Same for girls - think Steffi Graf.
In the 20th century people started using Steven instead of Stephen because that sounded like what they said anyway. No problem there. Stephen is the more traditional form, and Steven the more modern. They are pronounced the same.
Stephanie has always had a short e sound in the first syllable, which is why nobody ever says STEV-a-nee, so the spelling has never changed.