Category
Phones and mobile
SIMs, eSIMs, low-cost plans and switching carriers — the basics of phone contracts and mobile data, so you can decide for yourself.
Learning path
Learn phones and mobile from the ground up
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Articles
16 articles
Phones and mobileThe "5G" icon does not tell you everything: 5G SA in Japan, and a draft rule change for budget SIMsJapan's communications ministry published 5G rollout figures for March 2026 on 30 October, and on 27 October announced a consultation on revised guidelines to help budget SIM providers offer 5G standalone. What SA is, how to read the figures, and what to check when choosing a phone or plan.Phones and mobileEmails posing as the tax agency or points offers that push malicious apps onto AndroidJapan's Council of Anti-Phishing has reported a run of emails that pose as the National Tax Agency, e-Tax or points programmes and lead Android users to install malicious apps. This explains the shift from typing details into fake sites to installing apps, the settings that help, and what to do if you installed one.Phones and mobileBefore You Upgrade Your Phone: What to Check FirstWhen you switch phones, back up your data, check how two-step verification and authenticator apps carry over, sort out your SIM or eSIM and payments, and erase the old phone last. Based on the official iPhone and Android help pages.Phones and mobileSIM Card Not Recognized? Causes and the Order to CheckIf your phone says there is no SIM card, check in order: whether your contract is active, a restart, whether the line is on, how the SIM and tray are inserted, SIM lock, and carrier settings. Also covers eSIM and APN cases, based on official iPhone and Google Pixel help.Phones and mobilePhone Suddenly Shows No Service? What to CheckWhen your phone suddenly shows No Service, narrow it down in order: toggle Airplane Mode and restart, check that your SIM or eSIM line is on, then your location and signal, your contract and payments, and your carrier's outage information. Based on official iPhone and Google Pixel help.Phones and mobileWhy Low-Cost SIMs Can Slow Down at Certain Times of DayLow-cost SIMs in Japan can slow down at lunchtime and during commuting hours because many users share the fixed capacity the provider rents. How this works, based on Japanese government sources, how to rule out other causes, what to do at busy times, and what you can check before signing up.Phones and mobileHow Far Do 3GB, 10GB and 30GB Go? A Rough Guide to Data UseWhat you can do with 3GB, 10GB or 30GB depends heavily on video quality and habits. Rough per-activity figures compiled by Japan's Ministry of Internal Affairs and Communications, converting plans into hours of video, checking your own usage on iPhone and Android, and settings that cut data use.Phones and mobileLost Your Phone? What to Do First, in OrderIf you lose your phone, locate it from another device, mark it as lost to lock it, contact your carrier, check your accounts, and report it to the police. Covers Find My on iPhone and Find Hub on Android, and what to consider before erasing remotely.Phones and mobileSeven Criteria for Choosing a Mobile Plan That Fits YouChoose a low-cost SIM or mobile plan in Japan by how you use your phone, not by rankings. Seven criteria, from data and calls to busy hours, support, family discounts, your device and cancellation terms, based on Japan's official mobile phone portal, plus a template to fill in.Phones and mobile"Storage Full" — But Which Storage? Your Phone Versus the CloudWhen a "storage full" warning appears, is it your phone or your cloud account? How the two differ, where to see a usage breakdown, why deleting synced photos can reach every device, and how freeing space differs from deleting.Phones and mobileDoes Deleting an App Delete Your Data? Where It Lives and How to Back It UpWhat happens to your data when you delete an app depends on where it is stored. On-device, cloud and exported files, iPhone's Offload versus Delete, why sync is not backup, and how to check an export before you rely on it.Phones and mobileWhat Is a SIM Card? How Your Phone Gets on the NetworkA SIM card is the small chip that tells the mobile network your phone may use a particular contract. How it relates to your phone number, the difference between a physical SIM and an eSIM, what still works with no SIM, SIM sizes, and SIM locks.Phones and mobileWhat Is MNP? Switching Mobile Carriers in Japan Without Changing Your NumberMNP lets you keep your phone number when you move to another mobile carrier in Japan. The one-stop and two-step methods, the MNP reservation number, when your old contract ends, fees, and what to check first: carrier email, family discounts and handset payments.Phones and mobileWhat Is a Low-Cost SIM? Why It Is Cheaper Than the Major CarriersIn Japan, a "low-cost SIM" is mobile service from an MVNO that rents network capacity from a major carrier. Why it costs less, how it differs on busy-hour speed, shop support, calls and family plans, and what to check before switching.Phones and mobileWhat Is an eSIM? How It Differs and What to Watch When UpgradingAn eSIM is a chip built into your phone that receives your carrier contract over the network. How it differs from a physical SIM, how activation works, when you need a reissue, a safe order for switching phones, dual SIM, and using it abroad.Phones and mobileMNO vs MVNO: How Budget SIM Plans Work in JapanAn MNO builds and runs its own mobile network; an MVNO rents capacity on that network to sell its own service. How budget SIMs fit in, how carrier sub-brands differ, why speeds drop at busy times, and what to compare, without recommending any company.