LTE has been deployed globally, but it being an all IP technology implementing voice services has always been a challenge in case of LTE. Voice services continue to be an important source of revenue for communication service providers and various technologies have been leveraged to offer voice services in LTE. However, IP Multimedia Subsystem (IMS) based Voice over LTE (VoLTE) has emerged as the most popular technology to provide voice services in LTE.

According to GSA 186 VoLTE capable phones have been announced by leading vendors and 80 operators in 42 countries are investing in VoLTE deployments, studies or trials including 14 operators who commercially launched HD voice service using VoLTE.

This white paper provides comprehensive insights on how to implement VoLTE for UEs while guaranteeing Quality of Service (QoS). The paper also addresses the various VoLTE client architectures and discusses the pros and cons of each. The various aspects discussed in the paper include:

  • Various LTE voice technologies: The paper provides a detailed comparison of the most important voice technologies including CSFB (Circuit Switched Fall Back), SV-LTE (Simultaneous Voice – LTE), VoLGA (Voice over LTE via GAN), OTT (Over The Top) and VoLTE. It also discusses the various challenges in implementing each of this technology and why VoLTE is the best option amongst all
  • Implementing VoLTE for phones: The paper delves deep into the various aspects to be considered while implementing VoLTE for UEs including SRVCC (Single Radio Voice Call Continuity), PS-PS handovers, messaging (SMS) and the various VoLTE client architecture options – Application Processor (AP) centric architecture and Baseband Processor (BP) centric architecture.
  • VoLTE UE embedded software: The paper talks about how to optimize the embedded software to get the maximum out of the available processing power. It also discusses the various power management techniques that can be leveraged to extend the battery life, a major consideration in case of VoLTE