If you have ever used a corporate phone system, you are probably familiar with the concept of dialing ’9′ to get an outside line. That allows employees to simply dial extensions to communicate internally, but still use the normal plain old telephone system for placing calls outside of the company. Typically you dial ’9′ which results in a second dial tone and then you can dial the phone number like usual.
One of the most low-tech forms of attack on a voice system is for an outside caller to ask to be transferred to extension ’9011′. The ’9′ initiates the outside line dial tone, and the ’011′ is the code to initiate an international direct dial phone call. Transferring a caller to extension ’9011′ enables that caller to place international phone calls that end up being charged to the company because they originate from your phone system. It doesn’t happen often, but it is low-tech enough that it still happens on occasion. Make sure your users, particularly receptionists or customer service representatives that answer incoming calls frequently, are aware of this toll fraud scam and are educated to never transfer anyone to extension ’9011′.