Lawful interception on session border controller using SIP

With the convergence of Voice networks into IP world, VoIP has emerged as a cheap and easy-to-implement solution. Law Enforcement Agency (LEA) is any loca/national/international law agency monitoring unlawful activities. Lawful Interception (LI) is the term used to describe the technology and process of Intercepting communication lines, which could be either in the Circuit Network or the Packet Network for the purpose of providing Intercept Related Information (IRI) and Content of Communication (CC) to the LEAs. In the Packet domain the most convenient point in the network where Voice packets can be reliably monitored is the Service Provider´s (SP)network elements and possibly the Session Border Controllers (SBC). 3GPP standard recommends implementation architecture and suggestions for LI on VoIP networks. This paper discusses challenges faced by SP and LEAs to implement LI. It proposes the use of SIP protocol for the external interfaces from the SBC towards the LEA. In addition, it also proposes a solution to reduce the overheads faced by LEAs and SPs.