[js2]

I'm confused. How else would you pronounce it? Four hundred and four? Four-zero-four? That's just weird. :-)

I don't think I don't ever use "oh" for zero. FWIW, I'm from South Florida with New Jersey parents. The area code I grew up with is "three-oh-five".

[madcaptenor]

I think it might be different for area codes that end in a zero - I remember 610 (Philly area, where I grew up) usually being pronounced "six-ten". On the other hand, 215 was always "two-one-five", never "two-fifteen". But I agree for those with zero in the middle, like 404 or 305.