全球移动通信系统协会（GSMA）：2025年VoLTE部署指南报告（英文版）

LTE (Long Term Evolution), with its capability and optimized architecture to provide mobile broadband services, has been adopted aggressively by operators over the world and it is now provided by over 7541 operators around the world. As LTE is an All-IP network, the voice and messaging services provided over CS (Circuit-Switched) domain in previous generations needed to be adapted and evolved to work over an LTE network. VoLTE (Voice over LTE) addresses the migration to a PS (Packet Switched)