Preface
Voice communication has become mobile in a massive way and the mobile is the preferred way for voice communication for more than six billion subscribers. The introduction of high speed packet access (HSPA) also allows a large set of data services from smartphones, tablets and laptops to go mobile. The data volumes in mobile networks greatly exceed the voice volumes—from the traffic point of view, networks have already turned from voice dominated to data dominated. The next generation mobile radio system, called long term evolution (LTE), started commercially in 2009 and is designed to boost further the data rates and capacities. LTE radio is primarily optimised for high capacity data but can also support voice efficiently. During 2012, smartphones with the capability to provide a voice service using the LTE network are becoming available. This book describes how the voice service is supported with LTE capable terminals. The voice support in LTE is not as trivial as in second generation (2G) GSM and third generation (3G) WCDMA solutions where circuit switched (CS) voice was used, since LTE is designed only for packet switched (PS) connections. The voice service in LTE uses the voice over Internet protocol (VoIP)—called VoLTE (voice over LTE)—together with the IP multimedia system (IMS). There are also alternative solutions for supporting voice in the initial phase where the voice service runs on legacy 2G/3G networks while only data is carried on LTE. The voice solutions, ...
