NGN (Next Generation Networks) operators provide SIP services for their customers. Customers can call other operator’s customers via SIP services and SIP gateways. SIP gateways use SIP Trunks for trusted call initiation and cdr/invoice management. In this paper, a new method will be explained. The technique describes how you can detect trusted 3rd party SIP Trunks and initiate a call.
You can download it from the following link: https://packetstormsecurity.com/files/download/120346/Hacking_Trust_Relationships_Between_SIP_Gateways.pdf
Source: https://packetstormsecurity.com/files/120346/Hacking-Trust-Relationships-Between-SIP-Gateways.html