NTP VoIP platform: a SIP VoIP platform and its services

This paper introduces the major components of a SIP-based VoIP platform, referred to as NTP VoIP platform. Based on the NTP VoIP platform, the researchers can develop and deploy their applications and services. For lawful interception, we propose a monitoring system that provides call detail records and interception function. We also propose a conference system for audio and video conferences. In this paper, we provide detailed message flows to show how the monitoring system and the conference system work.