China’s top mobile telecom carriers have launched 4G service on the Nansha Islands, in an effort to safeguard the country’s legal claim in the South China Sea and to improve communication services for local people.

China Telecommunications Corp, the country’s third-largest telecom carrier by subscribers, has expanded its 4G signal to seven reefs of the Nansha Islands, giving islanders faster internet speed and enabling them to make video calls and conduct online commerce.

The move came shortly after the country dismissed the ruling by the Arbitral Tribunal in The Hague that China has no “historic title” over the South China Sea.

China Telecom’s larger competitor China Mobile Communications Corp also offers similar services around the region.

“The achievement highlights China’s determination to serve local people and passing ships. It also mirrors homegrown telecom companies’ cutting-edge technology,” said Xiang Ligang, a telecom veteran and CEO of the industry website cctime.com.

The Nansha Islands are in strategic shipping lanes, but they are far away from land, which makes it time-consuming and costly to build telecom infrastructure.

Su Xun, a China Mobile employee in charge of maintaining telecom equipment, said it takes 60 hours by ship to get to the Nansha Islands from Hainan province.

Additionally, telecom equipment is highly vulnerable to seawater corrosion, and it is difficult to ensure a stable supply of electricity to power 4G stations and to transmit signals.

However, Su said, “All of the problems have been properly handled and our efforts finally paid off.”

China Mobile has expanded its 4G signal to cover Yongshu Reef and Zhubi Reef of the Nansha Islands, after successfully launching service in the nearby Xisha Islands.

China Telecom has devoted more than 70 million yuan ($10.5 million) to telecom infrastructure construction in the South China Sea in the past four years. The State-owned company has spent nine months setting up eight base stations around the Nansha Islands.