China Mobile has deployed VoLTE over its TD-LTE network in Guangzhou, using equipment provided by ZTE.
The operator plans to follow the launch up with a wider nationwide rollout starting this year.
China Mobile's new VoLTE system uses ZTE's enhanced single radio voice call continuity (eSRVCC) switching technology and an IMS system. Voice calls have been demonstrated using smartphones with Qualcomm Snapdragon processors.
ZTE said the system was built using network systems and terminals from different vendors, supporting eSRVCC's suitability for all China Mobile's networks.
China Mobile vice president Sha Yuejia hailed the launch as a milestone for VoLTE's evolution. "The successful demonstration of VoLTE service speeds up the development of the entire industry ecosystem,” he said.
Last month, Hong Kong's CSL deployed VoLTE over its 4G network using the same ZTE technologies. South Korea's SK Telecom and LG U+ have been offering the service since mid-2012.