Since the 1950s, voice and video services such as telephony and television have established themselves as an integral part of everyone's life. Traditionally, voice and video service providers built their own networks to deliver these services to customers. However, tremendous technical advancements since the 1990s have revolutionized the mode of delivery of these services. Today, these services are delivered to the users over the Internet, and we believe that there are two main reasons for this: (i) delivering services over the Internet in IP packets is much more economical for voice and video service providers and (ii) the massive penetration of broadband (i.e. higher bandwidth) Internet service has ensured that the quality of voice and video services over the Internet is good enough for everyday use. The feasibility of a more economical alternative for voice and video services attracted many ISPs including Comcast, AT&T and Verizon, among several others, to offer these services to end users at a lower cost. However, non-ISPs, such as Skype, Google, Microsoft, etc. have also started offering these services to customers at extremely competitive prices (and, on many occasions, for free).

From an ISP's perspective, traffic classification has always been a critical activity for several important management tasks, such as traffic engineering, network planning and provisioning, security, billing and Quality of Service (QoS). Given the popularity of voice and video services over the Internet, it has now become all the more important for ISPs to identify voice and video traffic from other service providers for three reasons.