Intro
Mobile data may work perfectly in Japan, yet phone calls and SMS often fail.
Foreigners struggle with missed verification codes, dropped calls, and services that require Japanese numbers.
This becomes a serious issue when registering for banks, deliveries, or online platforms.
Causes
Japan treats voice calls and SMS differently from data.
Many services block:
- VoIP numbers
- Foreign-issued phone numbers
- Data-only SIMs
SMS filtering is particularly strict due to fraud prevention regulations.
Japan-Specific Issues
- Many services require domestic SMS verification
- VoIP numbers are frequently rejected
- Short codes often fail on foreign lines
- Call routing favors domestic carriers
- Emergency numbers may not work on data-only SIMs
These issues surprise users who assume phone functionality is universal.
Step-by-Step Fixes
- Confirm whether your SIM supports voice and SMS
- Avoid data-only plans when long-term
- Register a Japanese phone number early
- Test SMS short codes immediately
- Avoid VoIP numbers for official services
- Keep one physical SIM for calls
- Use Wi-Fi calling cautiously
- Avoid switching SIMs during verification
- Save carrier support numbers
- Use consistent phone numbers
- Expect delays in SMS delivery
- Choose Japan-compatible voice plans
Best Services / Best Plans
Foreigners often rely on:
- ☆SIM☆
- ☆Mobile☆
These provide proper voice and SMS compatibility in Japan.
FAQ
Why do verification codes never arrive?
Short codes often block foreign numbers.
Are VoIP numbers unreliable?
Yes, for official services.
Do emergency calls work?
Only on supported voice plans.
Is SMS still important in Japan?
Yes, for verification.
Can I keep my foreign number?
Yes, but expect limitations.
Conclusion
Voice and SMS issues are structural in Japan.
A Japan-compatible ☆SIM☆ plan prevents most problems.
