China Mobile (NYSE: CHL; 0941.HK) subsidiary Shanghai Mobile recently launched a "secondary number-switching" service, allowing subscribers to receive an additional mobile number, usable concurrently with their main number, without any need to change mobile phones or SIM cards. Users of the service will be able to switch freely between the numbers when placing or receiving calls and sending or receiving SMS messages. Subscribers will also be able to "turn off" their secondary numbers, or switch secondary numbers multiple times - so that when they have to provide contact information, they can give out their secondary number in order to protect the privacy of their primary number.