AFAIK, if you use a (non-China) foreign SIM card to roam in China, Google/Facebook access is not block when using mobile data on the foreign SIM card to access Internet.
Just FYI, one (more) possible option to consider below:
Starhub prepaid SIM card has a feature called Happy Roam -- which supports mobile data roaming to 10 countries -- INCLUDING China.
ALL mobile data purchased on Starhub prepaid can be used at no additional (roaming) cost in those countries supported by Starhub Happy Roam. See HERE:
http://www.starhub.com/personal/mobile/mobile-phones-plans/prepaid-cards/happy-roam.html
As with all other prepaid SIM cards, there are various (mobile) data plans you can use on Starhub prepaid SIM, see HERE:
http://www.starhub.com/personal/mob...ards/data-add-on-plans/prepaid-data-plan.html
You can also "stack" prepaid mobile data plans. An example of prepaid mobile data stacking below...
E.g. from above Starhub prepaid link -- the following mobile data plans are available:
- $5 1GB data plan valid for 3days
- $1 10MB data plan valid for 7days
You can consecutively buy (3 x $5 1GB 3days) + (1 x $1 10MB 7days), total spent is (3x$5 + 1x$1) = $16, combined you get...
(3x1GB + 1x10MB) = 3.01GB valid for 16days (3x3days + 1x7days)
Above is exactly how I stack to get 3GB mobile data valid for 16 days -- using Starhub prepaid SIM -- when I had a 2 weeks overseas trip the last time.
Make sure you activate roaming & set correct settings before using the mobile data on Starhub prepaid SIM overseas, see HERE:
http://www.starhub.com/personal/support/mobile/roaming/prepaid-roaming/happy-roam.html
Starhub also has a mobile app called "Happy Prepaid" which is available on both Google Playstore & Apple app store:
https://play.google.com/store/apps/details?id=com.starhub.happy
https://itunes.apple.com/sg/app/happy-prepaid/id981031677?mt=8
The "Happy Prepaid" app makes it easy to check remaining mobile data balance or buy more mobile data (if required).
When come back to Singapore...
Any unused/balance Starhub prepaid mobile data (still) within validity period -- can of course also be used here locally.
Hope the above helps.