If you can live with per area-code resolution, you can get the mapping database for free anytime from the North American Numbering Plan Administration at http://www.nanpa.com. You can download it in Excel format, which can then easily be inserted into a SQL database. You can get regularly updated area-code and exchange databases that'll give you data down to the city level, but those will cost you. I forget where you get them but a little directed Googling should turn it up for you.
Once you have the database, IPCC Express with the appropriate licensing for database dips can do the job. It would look at the ANI of all incoming calls to your sales number, look in the database you create for a mapping of ANI to a group/destination DN or however you want to arrange it, and perform the redirect. Nobody has to run the Agent Desktop software if you don't want that, you can just have IPCC Express do a simple transfer.
