Table of Contents Preface: Why Do Industrial Scenarios Need Voice Communication? Basic Concepts of VoIP and SIP 2.1 What is VoIP? 2.2 What is SIP? Role of Industrial Routers in VoIP/SIP Systems Typical Application Scenarios of VoIP/SIP on Industrial Routers 4.1 Industrial Site Voice Intercom 4.2 Unattended Site Remote Calling 4.3 Voice Alarm and Linkage Systems 4.4 Industrial Private Network/Industry Private Network Voice Communication Key Technical Support for VoIP/SIP by In