Traveling to Japan - turn off celluar or turn on Airplane Mode?

My wife will be traveling to Japan next week. She plans to rent one of those pocket wifi devices to tether her phone and computer to.

So, to eliminate the possibilities of getting charged overseas roam charges, which should she do: Just turn off cellular data or turn on Airplane mode?

From what I understand (and please correct me if I am wrong), turning off cellular data will allow for Wifi Calling, so that’s a bit of an advantage in case she gets a cell call from the US. (BTW, does that also allow for SMS texts to come through?)

When I look at Airplane mode, it turns off cellular completely but no Wifi calling. But, today’s Airplane mode allows for connection to wifi only.

I know she could take out the SIM, but I think she worries about losing the SIM or damaging it. Thanks!

If she is going to use the phone for media and playing videos or music over Bluetooth, she should turn off cellurlar. Likewise, if she is using the onboard Wi-Fi (Wi-Fi calling, browsing the Internet, streaming etc.) she should just turn off cellular. If she is using wired headphones and local storage, then airplane mode will save battery power.

If she is flying from the US, most of the flight will be over the US or the Pacific, so no cell coverage anyway.

Interestingly, as shown at DefCon last week and discussed on MacBreak Weekly, on an iPhone, turning off Wi-Fi, Bluetooth etc. from the drop-down Control Center only disconnects current connections and won’t reconnect them until the following morning, but they remain active. You really need to go into the Settings and turn the radios off there, if you really want them turned off.

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Surely turning off roaming would do what you are looking for?

My experience of WiFi calling and travelling from the UK Telcos is that it doesn’t work from abroad, it will only use cellular.


Does the same go for Airplane mode? I ask because on a recent flight, I turned on Airplane Mode and I could still use my earpods and Wifi (to connect to the plane’s wifi entertainment system).

I it seems that Airplane mode only turns of cellular access these days, as most airlines seem to offer wi-fi, so my comment about saving battery is a little redundant, but turning off cellular on the flight will still save power, even if wi-fi and BT are still active. (I haven’t flown in nearly a decade.)

So is there any real difference between turning off cellular and turning on Airplane mode?

Speed probably (as in the speed to do the turn off/on). Airplane mode is, surprisingly, meant for when you’re temporarily on an airplane. For those “lucky” folks who fly often, it’s easy to get in and out of that mode. If you want to be SURE it’s off, and stays off, turn it off in the settings.

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So technically, there’s no difference?

That’s my experience too. My understanding is for WiFi calling to work, your SIM needs to be active on a network. I then get the WiFi calling icon in my status bar.

But some people claim WiFi calling works with roaming turned off :thinking:

On the original question, I just ensure roaming isn’t enabled for my home SIM when overseas and purchase an eSIM. When you land I get a few ads trying to convince me to turn roaming on for their £5/day deal, but I ignore.

The biggest challenge when abroad for me is SMS 2FA. You can get locked out of credit card transactions if you don’t allow roaming.

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There is also the option of turning off data roaming but allowing roaming for calls.

Calls are charged on a pay as you go l, so if you don’t make or answer any calls then there is no cost. It’s also free to receive SMS messages, but non UK Telcos might be different.


Just an update on this in case others may want to know.

My wife is now in Japan. She turned off Cellular Data and has WiFi calling on. She is carrying a local pocket WiFi which is connected to NTT cellular network.

I just called her US cell number and she could receive the call! Excellent.

So my next question is will SMS texts go through? For example, if I’m in Japan and do the same setup, and I need to connect to my bank on my computer, I’ll next to get a text from my bank for 2FA.

If you only turned off cellular data then I’d say the SMS should work, but you should send her one to be sure.

She might be charged for your incoming call in case you didn’t know. Calls in WhatsApp etc would be free.

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She’s not very techy and doesn’t like to use other apps. How to send a SMS from an iPhone without it going through as an iMessage?

I’m not an iPhone user but I believe you can turn off iMessage in settings, so any messages you send will be via SMS. You can tell if they are blue instead of green.

How about facetime, don’t most iPhone users to use that?

Yes, that works. Just tinkering around to find out if text messages go through in case I’m ever back in Japan and need it for 2FA.

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One thing to remember, roaming SMS charges can be extortionate. Probably better to check the prices for her contract, before she gets bill-shock.

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Also, check your contract for WiFi calling charges. Checked mine ahead of our next trip in a couple of months.

My main UK SIM disables WiFi calling when abroad. My other, O2 SIM charges international call rates for them. Don’t assume it comes out of your inclusive minutes like it does when at home.

Can you check your bill online to avoid a shock in a month or so?

I think when you send an iMessage you can press and hold on the message just after sending it to switch to SMS.