Hong Kong/China dual number data SIMs with quality internet


Cross boarder SIM cards from China Mobile and China Unicom promise a single SIM that works in Hong Kong and China. Mobile data networks exit at the SIM card home location, so that means Hong Kong internet while in China. These SIMs are sold by two of China’s biggest state owned phone companies, they’re totally legit.

I’ve been skeptical of the cross border SIM cards because China Mobile 3G and 4G doesn’t work with many phones from outside China. Recently I reread an article posted in the Shenzhen_Hacker_Bei WeChat group and was surprised to see that my Samsung S6 dual SIM phone supports the China bands (TDD-LTE on bands 38, 39 and 40). Today I’m in Hong Kong today with no other mission, so let’s go to Aplui street market and try them all. Sham Shui Po, exit C2. Walk forward one block to the phone card booths.


I bought both China Mobile ($100) and China Unicom ($90) cross border cards.

The China Unicom SIM works with common international standard 3G frequencies in Hong Kong and China. This will work in most phones. Unicom doesn’t own their infrastructure in Hong Kong though, so coverage is smaller and data slower.

China Mobile SIM works on odd-ball Chinese 4G frequencies that are only supported on the latest iPhone 6 and Samsung S6 phones. A typical international phone will be stuck with Edge network in Hong Kong and China. However, if you can support the frequencies China Mobile owns all their own infrastructure so it is generally faster and cheaper.

Data plans are similar. Unicom is my carrier in China: 500MB for 30days, $68. That’s not gonna be useful to me. China Mobile seems better at 1GB $118 or 2GB $198 for 30days 4G data. Plus some recharge bonus. The card only has $60 stored value so I also bought $100 top up card.


China Unicom does H+ in Hong Kong. It does appear to roam and you get an SMS warning to turn roaming on.  China Mobile connects 4G in Hong Kong and seems much speedier than Unicom.  Mobile charges to receive calls, which seems awful American of them.  Mobile’s coverage is much better. I lost Unicom SIM data connection several times in way to Lowu/Lohu

Unicom card works in Japan for a reasonable fee. Great cause you can’t buy a sim in Japan as a foreigner. However, for Japan there are much cheaper tourist cards on Taobao from other China suppliers.

Border crossing was great. Even with a dual sim S6 I normally have to poke 6 or 7 times to swap SIMs and data speed. The cross border SIM worked seamlessly.

My feeling is if you’re here for a week or so then Unicom is the best bet as it works with most phones on 3G. If you have a brand new iPhone or the dual sim S6, then mobile offers better options, especially for long term business trips in excess of a month. Both can be recharged online, but Unicom can also be charged at shops in China.


China Mobile is 4G+ in China. Shows as roaming.  Its super fast and I can confirm that nothing is blocked. Unicom sim took a minute to get going but it shows H+ still roaming. Again, nothing blocked and quite fast. I think Mobile has the edge though. They own 100% of the wireless and fiber infrastructure.


My plan is to keep the China mobile card and use it for data in China and Hong Kong. It is cheaper and all around better than dealing with separate cards.

Join the Conversation


  1. Is this US or Hong Kong dollars? I was surprised data subscriptions wasn’t cheaper when I just visited Shenzhen, Hong Kong and Japan. The cheapest and best solution to us in Japan was renting a wifi 4G modem from the hotel. In hong Kong, many hotels offered free smart phones with unlimited data during your stay, which was very convenient.

  2. NOTE: all prices are HKD ($100 HKD ~ $13 USD)

    One month experience with the China Mobile HK SIM since writing this post:

    1. 2GB of China Mobile data seems to deplete crazy fast. Normally I use less than 800MB on my Chinese-based SIM, but I went through “4”GB in a month with the Hong Kong China Mobile SIM. Must be all the CND/Google/Twitter hosted crap that my China SIM helpfully blocks automatically. Or China Mobile HK sucks at measuring data.

    2. If the data bundle runs out, you have to go online, disable the current bundle, then reactivate another. You can’t do it from the phone. This is annoying.

    3. Mobile provides no billing history, so there is no way to know what happens to your money. I loaded $300 credit plus 2GB data bundle before going on a short trip to Vietnam. When I landed in Vietnam the SIM was tagged for theft and the account suspended. I called China Mobile HK and they reactivated the SIM, but the $350 credit (with bonus) and 2GB data bundle were all gone. Again, because there’s no billing history I had nothing to point to as evidence of the problem. For this reason, especially, I plan to switch the the China Unicom HK SIM instead and give it a go.

    4. Purchasing a (24 month minimum!) subscription/contract from either HK Mobile or HK Unicom is actually MORE EXPENSIVE than using a prepaid SIM. The main advantage of the contract is a huge plethora of phone minutes that teenage me would love, but adult me would never touch.

  3. re China Mobile: You can cancel the data package from your phone by dailing *103*02# and book a new 2GB data package by dailing *103*200*06# when you ran out of data.
    Also I took my card to Germany and Sweden where it worked flawlessly for receiving SMS, something the China Unicom SIM can’t do, it just does not work out of Hong Kong, Macau, China and Taiwan (maybe also some other asian countries)

Leave a comment

Leave a Reply to Simon Cancel reply

Your email address will not be published. Required fields are marked *

Notify me of followup comments via e-mail. You can also subscribe without commenting.