Gordy
My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.
![]() ![]() |
Gordy
My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.
Please support Geekzone by subscribing, or using one of our referral links: Mighty Ape | Samsung | AliExpress | Wise | Sharesies | Hatch | GoodSync | Backblaze backup
Gordy
My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.
I spent several years consulting on voice security in the UK for the likes of the Ministry of Defence, UN, local government, law enforcement agencies and private companies. Although my consultancy covered all aspects of voice security such as call encryption, evesdropping and war-dialling a large section of my work was around discovering, quantifying and preventing toll fraud. This is exactly the type of scam that has been publicised in this mornings Herald.
In short the fraud is usally achieved by dialling into a pabx that is local to you and then dialling out to an international destination from the PBX. You pay for a local call and the PBX owner pays for the second leg international call. The facility to do this is usually called DISA (direct inward subscriber access) and used to be very popular when international calls were still considered expensive. The legitimate use for such a facility would usually be something like 'company A does alot of business with company B in the UK. Executives at company A need to call Compnay B a great deal in the middle of the night. Rather than incur large toll bills on the executives home number we will use DISA.
DISA is not so popular these days as companies freely give mobile phones to their users, plus international calls have come down enormously in the last 10 years. If DISA is required (as it can be used for other purposes) then as with all these things it needs to be configured correctly.
1. Authentication through CLI
2. password authentication should lock users out after 3 attempts
3. the lock out should reset after X minutes
4. if 3 more failed attempts are made then the lock out time should double i.e. 2 x X
5. regular daily reporting needs to be performed on that DISA number to monitor for fraud
6. thresholds should be applied to the facility so that 1,000's of calls/dollars cannot be racked up in a single night
7. staff such as operators need to educated about transferring external callers to external numbers.
Telstra and WxC are correct when they say it is the customers responsibility to ensure that their PABX is configured correctly against toll fraud. HOWEVER, I personally believe that all telcos have the responsability to monitor circuit usage and when obvious fraud is occurring the ability to shut that circuit down. BT resisted this for years, but once one of their competitors offered the service then everyone started to.
Incidentally, the largest fraud I ever discovered was over £1,000,000 that the customer knew nothing about as they didn't report on / check their bills. And that was a police force !!!!
cheers
db
You can never have enough Volvos!
Gordy
My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.
![]() ![]() |