Networks carry various kinds of traffic and ISPs are keen to analyze the traffic so as to be able to support QoS on the distinct traffic flows. Traffic can be broadly categorized into two types: plain traffic and encrypted traffic. Further, each of these traffic types is based on either a standard protocol or a proprietary protocol. While it is fairly straightforward to analyze traffic that are based on standard protocols, it is extremely difficult to analyze encrypted traffic based on proprietary protocols. A system for Skype traffic detection involves analyzing encrypted traffic based on proprietary peer to peer protocol. The proposed approach is based on building Skype traffic models and using the same to determine Skype traffic in the network traffic.