China United Network Communications Group Co., Ltd. (China Unicom) and CTM have launched their first outbound 5G Standalone (SA) international roaming call, marking a major milestone in cross-border communications. The call covered three essential functions: VONR voice calls (5G ultra HD voice), high-speed internet access, and short message service (SMS).
This milestone was the result of close cooperation between the two companies in advancing 5G SA roaming network deployment. It leverages the extensive experience of China Unicom’s Beijing branch in SA network implementation and CTM’s technical expertise in SA deployment in Macao, enabling seamless integration between the two networks.
The voice call used VONR technology to deliver end-to-end high-definition communication over a 5G HD voice network. Data services were powered by CTM’s 5.5G network, which supports 200 MHz carrier aggregation, enabling ultra-fast download speeds suitable for 4K video streaming, cloud collaboration, and other bandwidth-intensive applications.
Notably, this is the first time that SMS services have been successfully implemented under a 5G SA architecture for international roaming. The service enables seamless sending and receiving of SMS across borders, with latency controlled to within 100 milliseconds — meeting the high-sensitivity requirements of use cases in finance, government services, and cross-border notifications.
This successful test not only deepens 5G SA network integration between the Chinese mainland and Macao but also lays a solid foundation for the future commercialization of 5G SA international roaming. The two parties have advanced the implementation of 5G non-local roaming technologies, allowing users to access the partner SA network in cross-border scenarios without changing SIM cards or phone numbers.
Beyond technical innovation, this milestone also strengthens connectivity between the Chinese mainland and Macao and sets the stage for future cross-border collaboration in smart city development, industrial internet, and other emerging fields.
(Executive editor: Cui Feng)
