There was something called remote or expansion market numbers. I cant remember whey they call them.

Another option is VOIP. With this option you get a remote NPA and the call is transfered over a more cost effective medium (and yes VOIP is "safe" as long as you have a good carrier, 100% of the major call centers I work for use VOIP).

Why do you need more then one DID per NPA?

For this volume you should be paying .05 per DID, thats what I am paying with a major carrier.