Low cost and convenience has made peer-to-peer VoIP call increasingly popular. These calls are secured by low latency network which made them anonymous and to some of the people – secure. However, secured is a very subjective word; it also mean that low latency anonymizing network allow the terrorists gets the opportunity to communicate in a secured way. Law enforcement agencies usually require call identifying capability to trace the call or conduct lawful electronic surveillance. The rapid proliferation of Internet telephony has raise serious threats in providing same quality call tracing. For e.g. a propriety signaling protocol could setup VoIP calls and VoIP traffic could be encrypted effortlessly.

How VoIP has proliferated Anonymous callings

VoIP uses a proprietary peer to peer protocol and popular companies like Skype uses it. These types to calls are hard to trace. However the owners of Skype (Microsoft) may give metadata access to law enforcement agencies to trace these calls to some extent. But if you wish to be untraced, you can make a fake email account and use it only for making Skype calls only.

Another easy way is Google Voice. You real identity can remain be hidden yet you can create a throwaway Google account and receive calls in your Google interface without disclosing your real phone number.  This also has to be kept in mind that in VoIP telephony, the network traffic flows through the cheapest routes and not through to shortest path. A call from US to Canada may pass through servers placed in China which makes it very difficult to trace by LEA.

Solution

To counter these negatively secured calls, various techniques are developed but the most popular is watermark technique. The key idea is to embed a unique watermark into the encrypted VoIP flow by slightly adjusting the timing of selected packets. This solution basically focuses on lawful interception of peer to peer VoIP call. Generally a VoIP packet passes through many peers in internet scenarios before reaching to their destination. So it is difficult to determine who is talking to whom. This solution presented watermarking technique, in which digital watermark would be embedded with VoIP signaling and media packets, which would help the law agencies to intercept VoIP call. This scheme is also known as packet marking scheme.

However, this solution is not providing the location information in terms of longitude and latitude. A fool proof security technique needs to fetch exact location information in order to enhance security, and to provide live tracking functionality. It should provide location information even in the case if someone is using the anonymous proxy server to establish the call. Device should not allow establishing call if it is not passing location information and location spoofing should not be allowed.