Don't bother. US wholesale termination is so cheap that no one will take you up on a no-CLI product unless you offer rates like .003/minute. With that rate, even if if you route 1000 minutes on each line (total 16,000 minutes), you'll only make $48.
Now, if you did the same thing in say.. Pakistan, you'd be able to make some money. But the key is for the locality you're doing this at to be overpriced to begin with. If you can offer half-priced routes and still be 2-3 cents a minute, you're in a good place.