Have you talked to local offices of T-Mobile, Sprint, (please not Cingular), and see if they offer a device.
I've seen many people at events with credit card machines hooked up to cell phones and I think either Verizon or Sprint (what do I know, I have T-Mobile) have wireless cards for computers so maybe there is something there.
That would give you the coverage and 15-30 days testing depending on your state before a contract becomes final.
Wayne has an idea with the modem; you would have to be sure a cordless phone could go that far as both a phone and the cordless are in the 2.4 MHz bandwidth and the FCC puts a limit on distance to avoid interfering with your "neighbor's" phone on 2.4 MHz.
Engenius has phones that would work that far but no modems. You might go to
www.engeniustech.com and ask them if they have any ideas.
