The essence of communication is breaking down barriers. In its simplest form, the telephone breaks distance and time barriers so that people can communicate in real time or near real time when they are not together. There are now many other barriers to be overcome. For example, people use many different devices to communicate (wireless phones, personal digital assistants [PDA], personal computers [PC], thin clients, etc.), and there are now new forms of communication as well, such as instant messaging. The unified communications concept involves breaking down these barriers so that people using different modes of communication, different media, and different devices can still communicate to anyone, anywhere, at any time.

Unified communications encompasses several communication systems or models including unified messaging, collaboration, and interaction systems; real-time and near real-time communications; and transactional applications. Unified messaging focuses on allowing users to access voice, e-mail, fax and other mixed media from a single mailbox independent of the access device. Multimedia services include messages of mixed media types such as video, sound clips, and pictures, and include communication via short message services (SMS). Collaboration and interaction systems focus on applications such as calendaring, scheduling, workflow, integrated voice response (IVR), and other enterprise applications that help individuals and workgroups communicate efficiently. Real-time and near real-time communications systems focus on fundamental communication between individuals using applications or systems such as conferencing, instant messaging, traditional and next-generation private branch exchanges (PBX), and paging. Transactional and informational systems focus on providing access to m-commerce, e-commerce, voice Web-browsing, weather, stock-information, and other enterprise applications.

Figure 1. Unified Communications and Its Components
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