When sharing your phone number with someone in another country, you must give them more information than just your local phone number. You will need to know your country code as well as your area or city code and phone number. The number of digits in the local phone number will vary from country to country. The format for writing them has been standardised.
Find your country code at CountryCode.org. These codes range from 1 to 4 digits. Some countries share the same code. The country code for the United States is 1. France's country code is 33.
Locate your city code. Some small countries do not use city or area codes; large countries will have hundreds of different codes. There are more than 300 area codes in use in the United States; France has five.
Identify the local phone number. The number of digits will vary from country to country. In the United States, a local phone number is seven digits. A local phone number in France is eight digits.
Write the complete international phone number. A United States phone number would be written: 1 608 222 3333. A phone number for Paris, France, would be written: 33 1 22 33 44 55.
In order to dial an international phone number, you also must know your International Direct Dialing number (IDD). This is the code required to dial from your country to another country and can also be found at CountryCode.org.