This document discusses Microsoft Lync as a replacement for PBX and VoIP systems. It provides an overview of Catapult Systems, a Microsoft consulting company, and their experience in delivering Unified Communications solutions using Microsoft technologies. The document demonstrates how Lync can provide a powerful replacement for traditional phone systems through its integration of instant messaging, conferencing, voice, and mobility features in one platform. It also highlights how Lync deployed in the cloud or on-premises can help businesses reduce expenses compared to traditional phone systems.