I saw this kind of fraud last year, we are a small carrier in Mexico city, the 
attackers send a burst of calls to one of our customer's 1-800 number, we 
realized by the huge amount of calls with really short duration -10 seconds at 
most- and it caused our customer was out of service temporarily as the PBX was 
exhausted. The attack came from an specific number from another local carrier, 
although it was identified the user was a PBX extension and allegedly abused by 
hackers hence no direct responsible identified. We block the originating number 
to prevent much more calls were completed.



From: VoiceOps [mailto:[email protected]] On Behalf Of Geoffrey Mina
Sent: jueves, 03 de abril de 2014 10:01 a.m.
To: VoiceOps
Subject: [VoiceOps] Toll-Free Fraud/Spam

We are seeing a relatively high number of strange calls hitting a portion of 
our Toll-Free numbers.  The ANIs are mostly disconnected/invalid.  When our 
system answers, we hear silence, a DTMF tone, and then a fast busy on the 
inbound RTP stream.

We are seeing this over multiple TF vendors.  Is anyone else seeing anything 
like this out in the wild?

Thanks,
Geoff


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