Originally Posted by moondog

People honestly do still make voice calls in China, Vince.

Common uses for travelers:
-restaurants/bars
-hotels (especially if you are staying in one with a good concierge)
-Uber/didi (technically feasible without voice, finding the car can be tricky unless you talk with the driver)

Originally Posted by STS-134

Yes, I'm sure it's somehow related to the APN used. Remember that no card changes its APN just because the user is roaming. When I am in China and I use my AT&T SIM, and I go to a site like whatismyip.com, it'll usually show an area like Washington or California, and the internet works as it should. With the HK cross border SIM cards, the APN "3gnet" is used, which is a HK APN, and the internet should also work like it should.

Only problem with doing this (unless you're using the dual number cross border SIM card) is that you're paying standard international roaming rates, which in the case of AT&T, is $120 for 800 MB. I did this last time though because running a VPN on my phone 24/7 was killing the battery.


You can probably just call a business phone number. Preferably one that has a prerecorded message when it answers. Or if you're like me, you do actually have friends in China that you can call. I'd set the data kill switch on my phone initially, so it doesn't consume any data at $0.80/MB, before I can get the number via SMS, top up the card, and sign up for the $118/1GB plan, if I were using the CUHK card.

It is useful to have a Chinese voice number. Last time I was at a Starbucks in China, they required a Chinese voice number that they could send an SMS to before I could get on the WiFi. Not sure why they have the system set up that way (here in the US all Starbucks just run open wifi) but it does require it.

Originally Posted by jamar

Try dialing *118*35# before trying to make a voice call and see if that works. Otherwise I use 400-888-0808 (JAL Customer Service) as an initial voice call.

Originally Posted by vincepoy

Interesting about the IP since I didn't think they would be able to route IP's like that as I always thought it had to be served by the carrier you are getting the wireless signal from as BGP4 is usually done by larger blocks and not individual IP addresses when it comes to routing. 3gnet is actually the APN used by China Unicom in China and is actually roaming when it's used in Hong Kong from the information I can find as the other APN is 3gwap. There is also uninet if one is using 2G.

https://apnsettings.gishan.net/apn/6...a/china-unicom

Originally Posted by vincepoy

You're right that I can just call a business phone number or any phone number since I think as long as the phone rings, the card would have been activated already or otherwise it won't even allow the phone number to ring.

Is the Data Kill switch basically the Connect to Mobile data setting on the iPhone? If so, couldn't I just be connected by WiFi and activate the card by using the Connect to Mobile Data and it will activate without using the $0.80/MB or will the phones only connect to the mobile data network when there is no WiFi connection?

Originally Posted by vincepoy

I think for the china voice number and wifi, maybe they just want to know who is using their WiFi and this is a good way to be able to track you down if needed.

Originally Posted by vincepoy

Uber wouldn't work for me since my account is registered to my Verizon Wireless number so it would not even be accessible when I'm in China

Originally Posted by jamar

That doesn't matter. I use Uber just fine when I'm in China even though it's registered to my American phone number. I just make sure to call the driver from within the app right after I get matched to them.

Originally Posted by STS-134

Actually, 3gnet is used for CUHK cards in HK too:
https://www.geodetic.gov.hk/smo/gsi/.../ntrip/apn.htm

Unlike on the voice side (where a phone takes on the characteristics of all other phones on the visited network), on the data side, all data gets tunneled through the home network. That's just the way the protocol for GSM/EDGE/UMTS/LTE was designed. I'm not sure of the historical reasons behind this; it could be that the home network might need to generate warning SMS messages as data gets used up and in order to do such a thing in real time, the home network must actually be processing the data in real time. In any case, we can use this to our advantage to get around annoying firewalls.


Sure, connecting when you're on WiFi works too. Data kill is basically anything that prevents the phone from using data over cellular. Android has a function under Settings->Data Usage->Restrict Background Data that prevents apps from using data unless connected to WiFi.


You know, I wonder if the CUHK cross border SIM would work on those types of hotspots, or if they flag those numbers as unregistered and don't allow access. Also, I am not sure whether the cross border SIM allows access to the China Unicom hotspot network in Mainland China either.

Originally Posted by jamar

That doesn't matter. I use Uber just fine when I'm in China even though it's registered to my American phone number. I just make sure to call the driver from within the app right after I get matched to them.

Originally Posted by vincepoy

That would be different since I thought they had to call you at the number registered to your account.

Originally Posted by moondog

As noted in my last post, in Chinese cities other than Shanghai, when you call the driver, you connect directly with his phone. Then, he can call you back on your phone if necessary.

Originally Posted by vincepoy

I've only used Uber here in the US a few times but that was 3-4 years ago and from what I remember, there is a generic phone number you call and it's based on ANI (Automatic Number Identification) since you have to call that number from the same phone number the account is registered under and it will route your call to the driver. If you try to call from any other phone number, it says something to the effect of sorry, but we are unable to locate you so its similar to how it works in Shanghai. Never saw it another way as this was also how it worked for Lyft and Sidecar too.

Originally Posted by turin39789

What is the best way to do text and voice over the data connection? I use google voice in the states, do I need to switch to hangouts or get skype?

Originally Posted by jackal

Scroll up. Lots of info in this thread.

Yes, you will need to use the Google Hangouts app to place and receive calls over VoIP. Assuming you go with a cross-border SIM, Skype and other VoIP solutions work as well (they aren't blocked in HK, and all data traffic is routed through HK).