If you are coming to China on a short term visit, one of the first thing to do when you arrive would probably be to get a prepaid mobile SIM card.
You would save heaps and avoid that expensive international roaming charges when you make calls locally. Also, it makes it easy and alot cheaper for your friends in China to contact or text you.
The prepaid cards are easily available at news stands for RM100 (about US$14).
To save you the hassle, I would recommend you to buy the card from news-stands or the smaller shops rather from the official telco shop. Let me tell you the reason why.
Sometime back, I needed a prepaid card and as I passed a China Mobile shop, I walked in to get one. I was told to get a queue number. As it was very cold outside, I did not mind waiting a bit more to get away from the treacherous winter. When it was my turn, the customer service officer asked me for my passport, address and other necessary details. I was puzzled and I asked him why this was needed when buying from other shops didn't require one and it was pay-and-go. If this is for tracking purposes it certainly would not be effective as scores of prepaid cards are being sold without being tracked. He didn't have the answer for me but told me this is the process.
Since I was already being attended to, I figured that I would wait.So, I waited for him to print all the necessary documents, the printer got jammed and I waited for him to fix that too. When the documents are ready, I had to sign on several copies of it before I can get my prepaid SIM card.
The entire process took about 20 mins just to get a prepaid card!
So next time, just get it from a news stand. Just pay-and-go. It would take you literally less than a minute.