[Asterisk-Users] Blocking the 'Do Not Call" List

[drodden]

Anybody have any experience with blocking numbers in the U.S's Do Not
Call list? 

We have a customer that will be getting their own Asterisk server from
us, and they want it to be check outbound numbers against the do not
call list; this is for a backup, in case there's a slip up and one of
their people try to dial somebody on the do not call list. 

The list has millions of numbers, and I don't think the extensions.conf
file could handle me listing all million+ phone numbers and making it
play a sound like "That number is on the do not call list", and then
creating a _NXXNXXNXXX extension at the very bottom. The list would take
up all it's memory. Anybody have a more elegant solution? Maybe an AGI
script to match the outbound phone number against a column in a table in
a MySQL database? Is there something similar already written that I can
just modify?

I know one of our T1 PRI Providers support this feature, but I don't
want to block the list from all of our customers, just this one
customer. Maybe they can do source+destination based blocking. I'd still
prefer it be done through Asterisk. Suggestions?