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- Reviewed by countrycalling.codes editorial team
Dialing sequence, step by step
- 1
Start with + on a mobile, or 010 when the Japan network requires an all-digit access prefix.
- 2
Add 1, the country calling code for United States.
- 3
Add the destination national significant number. There is no separate domestic trunk digit to remove. The digit 1 may be used before the ten-digit number for long-distance dialling, but it is also the shared country code in international notation.
Use +1 for a saved US contact. Japan commonly uses 010 for international access, while carrier-specific services can use another documented prefix before the +1 NANP destination.
Mobile and landline examples
X means a subscriber digit placeholder, so these patterns explain the transformation without publishing a private callable number. Save the + format; use the access-prefix format only for a call that starts in Japan.
| Number type | Domestic in United States | Save on mobile | Dial from Japan |
|---|---|---|---|
| Mobile | (202) 555-01XX | +1 202 555 01XX | 010 1 202 555 01XX |
| Landline | (212) 555-01XX | +1 212 555 01XX | 010 1 212 555 01XX |
How the international format is built
Portable contact format
+ 1 + national significant number
The + represents international access. It is display notation, not one of the E.164 digits.
Digits-only call from Japan
010 + 1 + national significant number
The first part routes out of the origin network and must not be stored as part of the destination.
E.164 limits the full international number to 15 digits and excludes international and national prefixes. See the E.164 and international-format guide for the reusable structure and regional exceptions.
Common mistakes for this route
- Treating a Japanese carrier-selection prefix as part of the US phone number.
- Dropping the US area code from the ten-digit NANP destination.
Country code references
Related country-pair guides
Standards and country numbering-plan sources
- ITU-T E.164: The international public telecommunication numbering planInternational Telecommunication Union. Verified 2026-07-19.
- ITU-T E.123: Notation for national and international telephone numbersInternational Telecommunication Union. Verified 2026-07-19.
- National numbering plan: JapanInternational Telecommunication Union. Verified 2026-07-19.
- National numbering plan: United StatesInternational Telecommunication Union. Verified 2026-07-19.
See our editorial and sourcing methodology.