Some years ago it was proposed to put faxes and wireless devices in
> the new area codes where a 10 digit number is not a disadvantage,
> but apparently this wasn't done very much.
A large number of small businesses, and probably some fairly large ones, too, share their fax on the same line as their phone. A 10-digit number would be a serious disadvantage. Several small businesses use cell phones as their business number for the public and their customers to call, and they, too would be at a serious disadvantage.