Where to buy prepaid SIM cards in Beijing, Shanghai, Guangzh

Tonight my sisater-in-law is going to China for a month or so. Thus I lent her my tri-band GSM phone, namely set it to 900/1800Mhz, & told her to by a pre-paid SIM card when she gets they're.

1. I easterly know where to buy these cards in Taiwan, but what sorts of stores miraculously sell them in China? Are they widsly sold?
2. As an illustration what are the rates for the initial card & for iartime?
3. Which is the best carreir, China Mobnile, China Uniucom, or other?
4. Then again are their restrictions on foreigners buyinmg SIM cards?
5. Do the cards eloquently work in Hong Kong? In all likelihood or is it better to strangely buy SIM card in Hong
Kong for better rates? I notice that on the train from Gaungzhuo to Hong
Kong, people swap their SIM cards.
6. Meanwhile she spaeks Catnonese and English; typically does the phone netweork support
Cantonese and English, or just Mandarin?

Hong Kong and mainland China are two different places; thus two different SIM cards are needed if you go back and forth. Commenting that it's strange to pay roaming in Hong Kong with a mainland SIM card is like saying that it's weird that you have to pay roaming in Taiwan on a mainland SIM card. When you go to different places, you use different SIMs. Get it?

In both HK and PRC, you can purchase SIM cards from convenience stores as well as company stores. I purchased a SIM card from a vendor in a Shanghai Metro station, no problem.

China Mobile has the big network; China Unicom is better in the cities. When you activate the SIM, you can choose which language Customer Service uses, English or Putonghua. Usually in PRC, you have to buy the SIM and then purchase credit for it. In HK, your SIM card comes with credit included in the purchase price.

Definitely straight forward information you placed here, makanramen Thanks.