An Overview of Global Phone Number Systems
Phone numbers worldwide operate under the ITU's E.164 standard, and every country has its own country code and numbering plan. Knowing how overseas numbers are put together helps both when you place an international call and when you have to judge an unfamiliar incoming number.
This article uses Japan's system as a baseline to compare the characteristics of major countries. See also Japan's country code and how phone numbers work.
Basic International Dialing Rules
International numbers come in two formats.
- E.164 format:
+[country code][national number](e.g., +81-90-1234-5678 = Japan's 090-1234-5678) - International prefix format:
[int'l prefix][country code][national number](e.g., 010-81-90-1234-5678 from Japan)
The "+" stands in for the international prefix of the country you are calling from. If you enter a number starting with "+" on a smartphone, you can keep using the same notation without memorizing the prefix of whichever country you happen to be in. The leading 0 of a national number is normally dropped in the + format, so Japan's 090-1234-5678 is written as "+81-90-1234-5678".
Major Country Systems
Japan (+81)
Japanese numbers run 10 digits for landlines and 11 digits for mobiles. A landline number is an area code (1 to 4 digits) plus a local exchange code (1 to 4 digits) plus a 4-digit subscriber number, adding up to 10 digits. Mobile numbers are 11 digits beginning with 090, 080, or 070, and they carry no regional information. The revision of the telephone numbering plan in December 2024 also added 11-digit mobile numbers beginning with 060. Special numbers such as 0120 and 0570 follow their own schemes.
United States (+1)
The United States and Canada share the North American Numbering Plan (NANP), and both use the country code +1. Countries and territories in the Caribbean take part in the same plan, so +1 on its own does not tell you which country the number belongs to. Numbers are a fixed 10 digits: a 3-digit area code, a 3-digit exchange code, and a 4-digit subscriber number. Nothing in the number separates landlines from mobiles, and area codes are assigned by region, such as 212 (New York), 213 (Los Angeles), and 415 (San Francisco). Toll-free calling uses several ranges, including 800, 888, 877, and 866.
United Kingdom (+44)
UK numbers follow a leading 0 plus an area code plus a subscriber number, for a total of 10 to 11 digits. London uses 020, Manchester 0161, and Edinburgh 0131. Mobile numbers are 11 digits beginning with 07. Freephone numbers use 0800 and 0808, business-rate service numbers use ranges such as 0870 and 0871, and premium-rate services use 09, so the ranges are split by purpose.
China (+86)
Chinese landline numbers combine a city code with a subscriber number for a total of 10 to 12 digits. Beijing uses 010, Shanghai 021, and Guangzhou 020. Mobile numbers are 11 digits beginning with 1, such as 13, 15, and 18, and the ranges are divided among the carriers (China Mobile, China Unicom, China Telecom). To place an international call from inside China, 00 is used as the prefix.
South Korea (+82)
Korean landline numbers are a leading 0 plus an area code plus a subscriber number, running 9 to 11 digits. Seoul uses 02, Busan 051, and Daegu 053. Mobile numbers are 11 digits beginning with 010, and ranges such as 011 and 016, which were in use in the past, were consolidated into 010. The structure resembles Japan's, so the breaks between the parts read the same way.
India (+91)
Indian landline numbers are an STD code (2 to 4 digits) plus a subscriber number, totaling 10 digits. Delhi uses 11, Mumbai 22, and Bangalore 80. When calling another area from inside the country, a 0 goes in front of the STD code. Mobile numbers are 10 digits beginning with 6, 7, 8, or 9.
Key Differences from Japan
Digit counts
Japan uses 10 digits for landlines and 11 for mobiles, but the counts vary from country to country. In the United States and Canada, both landlines and mobiles are a fixed 10 digits. Chinese mobiles are 11 digits, while landlines range from 10 to 12 depending on the region. India uses 10 digits across the board, so the digit count does not separate landlines from mobiles.
Regional identification
Japan identifies regions with area codes, and the area codes of the United States and the city codes of China work on the same idea. In some countries (Japan, Korea, India) mobile numbers carry no regional information, while in others (the United States, Canada) area codes apply to mobiles as well.
Distinguishing fixed lines from mobiles
In Japan the leading digits do the work, with 090, 080, and 070 marking a mobile. In the United States the number itself gives nothing away, so you cannot tell from the digits alone. In the United Kingdom anything beginning with 07 is a mobile at a glance. See Japanese mobile number basics for more.
Emergency numbers
Japan uses 110 for the police and 119 for ambulance and fire services. The United States uses 911, the United Kingdom 999, and 112 works across the EU. Our guide to emergency numbers around the world covers these in detail. Look up the numbers for your destination before you travel.
Things to Watch When Calling Internationally
Cost differences
International rates vary widely by origin, destination, and carrier. Even for the same destination, the rate changes with the carrier you signed up with and with whether you have an international calling option, so the reliable move is to check the rate table for your own contract before you dial. Calls between users of a calling app such as LINE or WhatsApp carry no call charge and use only data.
Mind the time difference
In standard time, Tokyo is 14 hours ahead of US Eastern, 9 hours ahead of the UK, and 3.5 hours ahead of India. While the United States and the United Kingdom are on summer time, each of those gaps narrows by an hour. Confirm that the destination's local time falls within business hours before calling.
Beware international scam calls
Suspicious calls from foreign country codes such as +1 or +44 may be international call scams. Do not return calls from numbers you do not recognize, and treat calls arriving from country codes other than +81 (Japan) with extra care.
Living or Working Abroad
If you want to keep your Japanese number while overseas, the usual approach is to put a local SIM in a SIM-free phone and receive calls to your Japanese number over VoIP. Whether a Japanese number can be used abroad depends on the carrier you are with and on the conditions each app sets, so before you leave, check what your own service says about making and receiving calls overseas. Virtual phone numbers are also useful for staying in touch across borders. For a long stay, obtaining a local number makes signing up for local services and reaching help in an emergency far easier.