In case anyone is trying to use an iPad in China I would like to offer some advice since I could not find it as I was trying to figure it out. I am in Beijing and today I bought a China Unicom SIM which was prepaid with RMB1200. I cut it down and was able to use it immediately. The APN, username, and password are all "3GNET". Worked immediately and is very fast (at least faster than the internet in my apartment here). The account consumes RMB80 per month as a minimum and that gives you 1GB of data. If you go over that it is RMB150 for 3GB, RMB200 for 5GB and RMB300 for 10GB of data. The SIM card I bought also came with a USB modem but of course once the SIM is cut down you can no longer use the SIM in it so that is a bit of a waste. The only thing that would be better for me would be a SIM that did not charge a minimum each month as some months I am not in China. But overall it is a good plan and very easy to implement. The card I bought is referred to as 无线上网卡 (wu xian shang wang ka).