It is a plastic film with a chip on top, which you can stick to your original SIM card and have them both work: voice with the original, and 3G with the SIM card sticker. In this way, you don’t have to compromise between 3G and voice quality.
China Mobile is the largest mobile service provider in China – and, indeed, the world – with nearly 630 million subscribers. China Unicom, despite being the official iPhone distributor in the country, is still trying to play catch up (see interactive chart below).
Although Unicom has the better 3G network it still cannot close the gap with China Mobile. Why? Although Unicom’s WCDMA is faster and more widely acknowleged as the best 3G network (compared to China Mobile’s homegrown TD-SCDMA frequency), its nationwide coverage can’t compete with its state-owned rival.A lot of Chinese folks buy unlocked iPhones and run them just on GPRS, simply so as to stick with their original number and not have to compromise on signal quality. China Mobile in some cities even provides SIM-cutting services for iPhone 4 users.
So with Unicom’s nifty new trick, you only have to take out your newly-purchased SIM card sticker, remove the adhesive on the back, cut a square hole on your own SIM card with the tool provided by Unicom, and stick the film on top. Now you have – effectively – two SIM cards. And according to Unicom, it supports both SIM and USIM. But you can’t use the two cards at the same time. As an alternative, you can forward your calls from one SIM to the other, but SMSs cannot be forwarded.
This card is a good effort from Unicom to steal some subscribers from its rivals, but the outlook is still unpredictable. Unicom still has the daunting task ahead of improving its network infrastructure, and persuading locals to pay more per month for its 3G services.