How do you write a French phone number?

A telephone number in France has 9 digits. As dialed within France, you dial a trunk prefix (usually 0), followed by the 9-digit number, for a total of 10 digits. From outside France, you dial your international access prefix (most commonly 00, but many countries use other prefixes), plus country code +33, plus the 9-digit number. On a GSM mobile phone, you can dial +33 (including the plus sign) and the 9-digit number.