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
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.
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?
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.
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.
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.