ical UC session might start with an IM between two parties that escalates to a phone call or web conference through the click of a button on the PC screen. That click connects the parties via audio, and another turns the call into video, if desired. If other people need to be added to the conversation, a look at the presence status of people on your buddy list lets you simply click-to-conference to bring them into the call. Presence has an important role in UC. It helps to know where one's intended recipients are and whether they are available in real time. To put it simply, UC integrates all the sys- tems a user might already be using and enables those systems to work together in real time. Most people associate presence with IM (IM "buddy lists"). But, in many business process applications, what is important is finding someone with a certain skill. In these environments, presence identifies available people with certain skills or capabilities. For example, a customer service representative (CSR) receives a call from a customer who has a question that is outside of the CSR's area of expertise. UC can enable the CSR to access a real-time list of available expert colleagues and then make a call that would reach the necessary person. This would enable the customer to receive an answer faster and eliminate rounds of back-and-forth emails and phone tag. Enterprises find that they can achieve an even greater impact by using UC capabilities to transform business processes. This is achieved by integrating UC functionality directly into business applications. UC Today UC has evolved over the last decade. Convergence took hold as a concept in the late '90s. Internet Protocol (IP) became the most widely accepted transport technology for data traffic. Around the same time VoIP came on the scene as a potentially disruptive technol- ogy for telecommunications. This convergence of voice and data networks has continued around the globe for the past several years. Today there are many networks that still haven't fully converged.