[VoiceOps] Fraud fun
troy at yort.com
Thu May 19 03:21:25 EDT 2011
On Tue, May 17, 2011 at 3:53 PM, Darren Schreiber <d at d-man.org> wrote:
> Hi folks,
> We have been hit twice in the past two days with calls to 011-252-XXXXXXXX
> (calls to Somalia I believe, and the originating IP is from Pakistan)
Others have suggested NCC-specific firewall policies. I'll put in a
plug for using per-country-code dialplan routes and omitting really
Obviously that won't work for worldwide wholesale transport carriers.
For everyone else, the most expensive CCs to call aren't worth the
trouble. There are very few folks with legitimate needs to call, say,
Sierra Leone, that aren't served by Skype. They don't represent enough
revenue to justify the risk.
Those few legit higher-volume folks are willing to prepay using
reliable methods. They're usually apologetic that their countries
receive enough fraudulent calls to need such a policy.
Basically scroll through
http://www.voicetrading.com/en/calling-rates.html and omit routes for
any country that's had a civil war in the past 20 years. Fringe
benefit: when a country code splits, you won't get caught with a rate
deck hole (see Timor-Leste, St Maarten).
If you want to get slick, have a call attempt to those country codes
page your admins as a honeynet (honeyroute?). Somebody's probably up
Doesn't prevent calls to expensive mobile routes in countries you do
reach, they're just a lot less interesting to fraudsters (woo, I can
call Proximus!?) and the per-minute costs are mostly way lower.
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