VoIP Voice and Fax Signal Processing

PREFACE

Voice over IP (VoIP) gained popularity through actual deployments and by making use of VoIP-based telephone and fax calls with global roaming and connectivity via the Internet. Several decades of effort have gone into VoIP, and these efforts are benefitting real applications. Several valuable books have been published by experts in the field. While I was building the team, and training them, and conducting several design and support phases, I felt like a consolidated view and material on VoIP voice and fax signal processing was missing. Several contributions in the form of white papers, application notes, data sheets, standards, several books at the system level, and specialized books on signaling, speech compression, echo cancellation, and voice quality exist. Fax processing is available in books mainly for a public switched telephone network (PSTN), several white papers on fax over IP (FoIP), and a lot of ITU recommendations.

In this book, I am trying to bring out a consolidated view and basic approach with interpretation on popularly used techniques mapped to VoIP voice and fax signal processing. As a summary, this book broadly covers topics such as PSTN and VoIP overview, VoIP infrastructure, voice interfaces, voice signal processing modules and practical aspects, wideband voice, packetization, voice bit rate on multiple network interfaces, testing at module level and as a total VoIP system, fax on PSTN, FoIP processing, FoIP anomalies, testing, FoIP bit rates, miscellaneous ...