You might have three area codes, but if you don't need to dial 11 digits all the time this means that these area codes still have some kind of geographic basis. In places where area codes are "overlayed," a new area code is introduced that includes places that already have their own area code -- and the new area code is used for all new phones from that point on. So a home with two different phone numbers could theoretically have two different area codes for its phones.
713 and 281 are geographical - at least as regards landlines - but 832 is an overlay here.