China Mobile's 400 million users will be allowed to switch to the carrier's 3G services with their current numbers from next year, the world's No. 1 mobile operator said on Monday. The move, which is expected to boost the homegrown 3G industry, will be trialed in three cities including Tianjin in northern China , Shenzhen, in southern China 's Guangdong Province , and Xiamen , Fujian Wang Jianzhou , China Mobile chairman.