China Telecom launches limited eSIM service for Apple Watch | Digital Asia

China Mobile, the world's biggest mobile operator, is the only carrier that does not offer the service in China, with China Unicom supporting use only in Shanghai, Guangzhou, Changsha, Shenzhen, Tianjin, Wuhan, and Zhengzhou, according to local media.

eSIM,

or embedded SIM, allows devices without a SIM slot to access a mobile network. It also allows an additional SIM to be added to a device without the need for a physical SIM slot. The information that is usually stored on SIM card is instead kept on a chip inside a device. The chip is rewritable, allowing for SIM information to be added and removed.

In the case of the Apple Watch, the eSIM shares a phone number with its owner's iPhone, allowing it to use the network without the paired smartphone around. The functionality is available on cellular-enabled Apple Watch models.

Chinese eSIM adoption got off to a rocky start in 2017 when the Apple Watch 3 was released. At the time, China Unicom had received a probationary license to offer eSIM services and did not pass the Ministry of Industry and Information Technology's formal approval process. The carrier was unable to handle large-scale use of China's Apple Watch Series 3 users and had to suspend the service. Apple also decided that  Apple Watch Series 3 customers are eligible for a refund in China.

China Unicom later relaunched its eSIM service in March 2018.

Apple showed it had learned from the eSIM debacle when releasing new iPhone models in September. Despite almost all new iPhones released worldwide supporting dual SIM functionality—one physical SIM slot and an eSIM—the new models in China, including the XR and XS Max, allow for two physical SIM cards.