Unified Communications cover a wide range to technologies. One can start with just controlling IP phones and making simple calls to others in the organization or outside your organization. Then there is a need to know the Presence information of other. How do I reach and interact with them? are they speaking on the phone? should one use Chat or are they traveling so one needs to reach them on their Mobile devices. How is Mobility accommodated in Unified Communication? Then there is Collaboration through Desktop application sharing or Conferencing with Voice and Video. This becomes complex as different technologies need to work with each other.
Cisco has its Solution Reference Network Design (SRND) guides that discuss Unified Communication for the Enterprise providing design guidance on how an Enterprise can bring the various technologies together for their users and provide them with a consolidated solution that takes into considerations some of their requirements and needs.