[Asterisk-Users] Validating a phone number

[Peter Hsu]

I'm concerned about people dialing out of our asterisk server to numbers 
they shouldn't be dialing.

Is there a concrete algorithm for determining whether a phone number is 
"normal".  i.e. calling this phone number would result in a normal long 
distance rate.

It seems like the pattern 1NXXNXXXXXX for the U.S. is fairly commonly used, 
but it wouldn't catch erroneous phone numbers such as "1411XXXXXXX" (and the 
other X11 numbers)

Is it just a matter of checking for these invalid area codes?  If so, is 
there a list anywhere that I could check against?

I tried googling this topic, but it's hard to find anything with such common 
keywords.  If anyone can direct me to a good resource, I'd appreciate it as 
well.

On athe same topic, I'm worried about area codes like 809.  Are there any 
other such area codes that should be avoided?

Thanks,
Peter Hsu