[Asterisk-Users] Dialing area question

[Clif Jones]

I am wanting to perform toll bypass using multiple gateways for outgoing
calls.
For example, if I call from location A to location B and I have a gateway in
location B I obviously want to use location B's gateway to make it a
local call.
I understand how to get the local prefixes from NANPA but my question is:
If there are additional numbers that are local (non-toll) calls from a
particular
calling area, how do I discover them.  Many adjacent calling areas are
accessible
via 7-digit dialing but you get usage sensitive charges which are
undesirable.
I just want to easily figure out which ones are free for an area without
going
through a huge search.  Anyone know how this works?  This has got to be
stored somewhere.