Hi all, looking for some advice on what kind of SIM products are there that allows one to get 3G on iPhone with data roaming.

So in the past, I have tried these 2 solutions from China Unicom
- monthly plan, for 60rmb/month you get 300mb data, allows data roaming to any other cities within mainland china. Problem with this is that you need to register with your passport (not a huge deal, takes ~30min). But you must continue to pay every month, and you must go into store for cancellation - this isn't as economical as I go there maybe once or twice a year and staying for a few weeks each time
- prepaid card, i think something under 100rmb for voice and 300mb of data. Problem with this is that data roaming is not included. eg. if I buy a SIM card in beijing and go to shanghai, my balance will drain in a few minutes because the included 300mb data is only for within beijing. I could buy another SIM card while in shanghai, but that meant a change in number and other people will not be able to reach me anymore.

So I'm looking for the following:
prepaid/pay as you go (so that for the majority of the year when I'm not in china, I don't have to pay)
SIM card/phone with data roaming (to avoid outrages roaming charges when moving between cities in china)
3G on iphone (I'm guessing China mobile is out of the question)

Thanks in advance for any suggestions!

You only need to go through the passport drill if you buy your SIM at an actual Unicom or Mobile store.

You can change your plan any time by calling their service numbers. This takes less than two mins.

There are data only Sims as well. I used to buy these for my mifi. Iirc you pay 300 for around 10g and have a year to use it.

I now think Unicom set b is the best way to go. Just turn it off when you're not in China. I have a 3g SIM but honestly this isn't a big deal because true 3g coverage is spotty even in bj/sh.

I thought the set b plan is only available to monthly plan, and I could only get it in the actual store?

The random prepaid cards I got were from newspaper stands around the city. I was also offered one upon arrival in the arrival hall, and some girl was selling it. But the balance on those SIM cards will drain so quickly if I move to different cities and use data.

Do you know where I can buy the data only SIM? 10g for 300rmb sounds very reasonable for a year.

You can select or amend any Unicom/Mobile plans over the phone.

The only places I've seen data only cards are electronics markets. Every decent sized city has at least one and bj has many. If you msg me with your desired city I will reply with options.

The SIM card that you have and the plan that you have are 2 independent matters. So you can buy the SIM anywhere you want. Understand that in the 300RMB package that Moondog is talking about, most of the data is "local data" and maybe one third is for "out of town".