Foreign SIMs and Great Firewall
 

If I visit China and just use data roaming on my UK SIM, do the Great Firewall restrictions apply?

I have been looking at getting a Hong Kong cross-border SIM, as I understand that these then avoid censorship without the need for a VPN. (Correct?). Is this unique to HK SIMs or does this apply to any foreign SIMs?

Sorry for what is probably quite a basic question but there is so much confusing and contradictory information online.

I have never tried myself but there are many reports that foreign SIMs are not subject to the Great Firewall.

Roaming bypasses the GFW—you'll still have a UK IP if you're using a UK SIM, and all traffic is routed directly through your home carrier.

data roaming is fine

Great, thank you all for confirming.

Yes, I used a Thai SIM card in China this summer and had no problem accessing Google, Facebook or Instagram.

Highly recommended to get a foreign SIM and any foreign SIM will work.

I bought the Thai one in Hong Kong as it was far cheaper than the HK cross-border SIMs.
From memory it cost 88 HKD for 8 days and 4GB of 4G + unlimited at 128 kbps..

The only thing to keep in mind is, if the Thai one is the one I'm thinking of, then it works with the China Mobile network. Not everyone's phones works well with their network, but I think that one is definitely a better value than the China Mobile HK SIMs.

There are many street resellers of Thai based SIM for data access all over different S and SE Asia regions.
However, there are some issues of the support of your phone and frequencies with their local roaming partner. I heard of people with US phones not getting connected.
Support is good if you speak Thai.

I don't think you still have a UK IP. You are accessing the internet inside China, you have a Chinese IP.

I am quite sure what is happening is the Great Firewall of China sees that you are a foreign SIM card, and does not enforce the restrictions.

Of course, this is all academic, the only thing that matters is when you use your foreign SIM card for GPRS internet, there are no restrictions. But as soon as you switch over to Wi-Fi inside China, you are restricted unless at a few select foreign hotels like a Marriott in Shanghai.

When roaming, I always go to www.whatismyipaddress.com

Every time I do this, it shows the IP address for the service provider in my home country and not of the country that I am roaming in.

Roaming data traffic is always "tunneled" back to the home country's service provider before being sent out into the public internet.

Made a small correction. It depends on your home carrier as their local roaming partner as well. That is a recent development in China.

Didn't know that! Just checked with my t-mobile US back up SIM card, I am in China now.

my home wi-fi shows my exact Chinese city location, turn off Wi-Fi and revert to LTE and now it shows at Pico Rivera, CA, ISP is T-Mobile USA.

I never imagined.... I thought of it as a type of VPN but reality is, it is a VPN.

Try going to some websites that are banned in China while in LTE mode.

I am in China every month. I use a China Unicom HK Cross Border King SIM, and it is not subject to GWoC blocking. More often than not, your IP (whilst on mobile data) is that of the APN server configured on your phone, so most likely the SIM card's home country IP.

When I bought my China Mobile HK cross-border SIM, the packaging specifically stated that you will be able to access websites such as Facebook while in Mainland China.