Use of foreign phone in Japan

[Lothor]

I know almost nothing about smartphones (I don't even have one), so please take this into account in your answer.
My twelve-year-old son would like a smartphone and my mother has one in Britain that she no longer uses. Can it be used in Japan?

 

[Majestic]

If its a relatively recent smartphone, your son should be able to remove the SIM card that is currently in the phone, and replace it with a SIM card bought here in Japan. This will allow your son to use that phone here in Japan. The SIM card is just a tiny chip, slightly smaller than a 1-yen coin that all mobile phones have (they are the things that tell the phone which network to connect to, and they manage the telephone and net traffic).

Japan used to be pretty strict about SIM cards. Docomo phones could only use Docomo SIM cards, and no phone company would allow their SIM cards to be used with phones bought overseas, etc...., but Japan has liberalized its mobile phone market in the past few years so there are all sorts of SIM cards available now.

There are prepaid SIM cards available from Amazon Japan, but you should also be able to buy them from any electronics store. The prepaid ones come with a fixed amount of data/voice time, so I'm not sure what happens when you run out of data: I don't know whether you buy a new one SIM card, or if there is some way to add data to the expired one. I assume you can add time, but you would need a credit card.

Amazon product
If your son just brings that phone to Japan and tries to use it as is, without changing the sim card, it probably will not work. The current SIM card won't know which network to connect to, and it will endlessly search for a UK phone network. (Or, if your wife was tech savvy and she arranged with her phone company to enable international roaming, AND the the phone is set up to automatically pick up foreign networks, the phone may miraculously work.. I kind of doubt this will happen though, unless your wife was a frequent foreign traveler and heavy data user).

 

[Lothor]

Majestic - thanks very much for the helpful reply!

 

[johnnyG]

You need to get some info about the specific model # of your mother's (old) phone.

Not just the name of the phone, like "iPhone 6S", but the actual model number. This specific detail will be available in the settings menu of the phone.

It's important because the 'same' phone can be manufactured so that it uses different bands (think radio frequencies) depending on the country that it is sold in. For example, iphones sold in the US don't work particularly well in Japan, since the range of common bands--those used in both countries--is not that wide. Believe it or not, some phone like an iPhone 6s that is manufactured for the US market, and an iPhone 6s for the Japanese market, are not the exact same phone on the inside (same situation for other makers).

In addition to the country where it was made to be used (and then the country in which you want to use it), different carriers here in Japan also use different bands (different frequencies). So your mother's old phone may work well (or better) on the docomo network than on softbank or AU. Or vice versa.

**

Once you have the specific phone model, go to a site like WillMyPhoneWork.net - Check if your phone works on a network and plug in make, model and number, and then go to the target country and carrier/network to see if it will work. (how well it might work)

While you could go with a major carrier, if that's what the results say, you should also consider an MVNO, and getting a 格安SIM. Depending on your choice there, the monthly plan cost could be some fraction of the cost of a major carrier. For example, for a number (voice) and 3GB/month, I pay ¥1400/month to IIJmio (which uses the docomo network). If you're a heavier user, you can pay more for 5, 10, 20GB/month as you please.

 

[johnnyG]

...The current SIM card won't know which network to connect to, and it will endlessly search for a UK phone network. (Or, if your wife was tech savvy and she arranged with her phone company to enable international roaming, ...a user).

Warning: International roaming can be expensive, and some would say exorbitantly expensive. Personally, I wouldn't use this 'feature' except in an emergency.

 

[nice gaijin]

Just another layer of complexity: If the phone was bought from a UK carrier, there's a chance it's "locked" to the carrier. At least in the US, once you've paid off the whole phone you can request the carrier to unlock it to use with other networks (or pay some 3rd party service to do it for you). The phone may work if it's unlocked, but there's no guarantee, for the reasons johnnyG mentioned above...

 

[Vincent3]

Speaking for US phones, last summer I learned that international roaming support depends on the model. I switched SIM cards in my wife and son's phone in the US according to my carrier's instructions, and they said international roaming was all set. Then they got to Japan and couldn't make calls. I went back and forth with the carrier, then did a web search and found that my wife and son's phones don't support it.