Today we use numerous methods of direct communications, for which we use a technical term Unified Communications. It is almost impossible to imagine the business world today without Unified Communications, which are improving productivity and reducing costs. The goal of using Unified Communications is to ensure a consistent user experience at any location and any device. Skype for Business, a Microsoft product, is one of the solutions for Unified Communications and is described in this thesis. The thesis defines and describes functional requirements. It also defines the concept of Unified Communications, followed by an overview of significant suitable solutions, verification of compliance with functional requirements and a presentation of a most suitable solution. The thesis then describes the Skype for Business 2015 Server, including installation topology, server roles and collocation possibilities. Practical part of the thesis covers Skype for Business 2015 Server installation and describes various required installation components. It also includes Skype for Business 2015 Server integration with an existing IP PBX business phone system based on an open source solution Asterisk.