Only 3G and 4G capable UK handsets will work in Japan. GSM-only UK phones don't work, as there's no GSM network. If you plan to make lots of calls or use mobile data in Japan, SIM cards are available to hire online or in-store. WiFi zones are also increasingly available in coffee shops, hotels and other public spaces.

Yes, you can use your UK phone in Japan, but the cost depends on your provider and the age of your device. Most modern UK smartphones (iPhone 12+ or recent Samsung Galaxy models) support the specific 4G and 5G band frequencies used by Japanese carriers like Docomo and SoftBank. However, "roaming" on a UK plan can be incredibly expensive, with some providers charging up to £6–£8 per day for limited data. A much better 2026 strategy is to use an eSIM (like Holafly or Airalo), which allows you to download a local Japanese data plan instantly without swapping physical cards. If your phone is older and lacks eSIM support, you can rent a "Pocket Wi-Fi" router at major airports like Narita or Haneda, which provides a high-speed bubble of internet for multiple devices. Just ensure your phone is "unlocked" from your UK carrier before you leave, otherwise, it will refuse to recognize any non-UK signal or SIM.