The VoTD-LTE call was conducted on China Mobile’s network in Guangzhou, which deploys ZTE’s TD-LTE technology and the core IP multimedia subsystem (IMS) platform. The call was carried out using 5-mode, 13-band smartphones powered by Marvell’s chipsets.
Currently, the three main methods to offer voice services to LTE users include: CS fall back (CSFB), dual standby and VoLTE. The CSFB solution requires operators to hand off voice calls to slower 2G or 3G networks. The dual standby solution requires terminals to support the 2G, 3G and 4G services simultaneously, with the 2G or 3G network dedicated to provide voice services. VoLTE is an IMS-based voice service, with voice transmitted as IP data, and can be entirely supported by the LTE network, without 2G or 3G networks. Compared with the CSFB and dual standby solutions, the VoLTE solution offers improved voice quality and energy consumption for terminals and lower latency.
