[ddeck]

For anyone travelling to China through HK, China Mobile sell a $15 SIM in their HK stores that will give you 1.5 GB of 3G/4G data in both HK and China for 10-days.

China Mobile have the largest network on the mainland and I've used it a number of times without issue.

This also has the benefit of allowing you to access any site that is accessible from HK (all) while in China.

Edit:

URL: https://www.hk.chinamobile.com/en/corporate_information/Prep...

[cflee]

If you only have a 3G device, or a 4G device that doesn't support the available FDD-LTE bands, you might be better off getting a China Unicom HK card instead. They have HSPA+ on 2100 MHz. Google services work fine on them.

The cards are hard or impossible to find within the HKIA transit area, so you will want to either pick it from a street retailer in HK, or order from their English webstore - http://www.cugstore.com/hk_en/. Street prices are usually cheaper.

(No affiliation, just a happy customer from a few months back. I got their "Greater China 30 Days Data SIM" because I was spending time in Macau and Hong Kong as well.)