Dual SIMs / eSim and preventing data use on primary SIM

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timmmay

20575 posts

Uber Geek

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Lifetime subscriber

#316141 19-Sep-2024 18:14

I'm going to the UK later in the year, I'm going to get a GiffGaff esim. I'd like to prevent using any data or calls on my NZ sim in my Pixel 8 and my wife's S22. This Google page says you go into settings and set which SIM you want data / calls / messages to use. Is it that simple? Are there any gotchas? I'll keep the phone in Airplane mode with WiFi on until I have the eSim set up, which I'll purchase and install in Healthrow or the hotel using their WiFi.

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tardtasticx

3075 posts

Uber Geek

#3284254 19-Sep-2024 21:15

Firstly these below details were from an iPhone so might vary for your android devices slightly.

Easiest way is while you’re in NZ go to mobile settings and turn of Automatic Network Selection.
When the list of networks come up, select your NZ telco and it’ll attach to it just fine.
While in NZ you wont notice any difference at all.

The magic is when you land in another country, your phone is still trying to attach to the network you manually selected. Since it doesn’t exist overseas obviously, it will fail to connect and wont get any service. Since automatic selection is turned off as well it wont even attempt to connect to another network to establish roaming. Most of the time (see below) it’ll just show no service on that SIM.

Then you can add any other SIM you like, and leave the settings on that new SIM as defaults. The automatic network selection is unique to each SIM, so your primary one has this off while the secondary has it turned on. Then set the secondary SIM as your data SIM and you’re good to go.

If you’re on OneNZ or 2Degrees, while overseas you can use WiFi Calling. I assume androids would do the same, but the SIM which isn’t used for data will use the second SIMs data connection to establish wifi calling connectivity. So you can use your NZ SIM in another country over mobile, but that SIM behaves as if it was in NZ using WiFI calling.

We’ve done this in Australia and Scotland, has worked perfectly each time for our OneNZ SIMs with a local eSIM for data.

Asteros

252 posts

Ultimate Geek

#3309071 14-Nov-2024 19:17

I've done some testing. Can confirm this works using previous settings described above.

TLDR One NZ Wifi calling on a foreign sim (with data) works overseas! - i.e. don’t need to go into Airplane mode and connect to a foreign Wifi hotspot or foreign Wifi network. You can make and receive calls and send and receive SMS as if you were on Wifi in NZ, but running on foreign 4g or 5g networks.