Calling a French phone number from abroad
A French phone number that looks like 01-23-45-67-89 can be called from abroad by dialing XX-33-1-23-45-67-89 where XX is the international prefix of the country you are calling from.

For example dial 00-33-1-23-45-67-89 from UK, or 011-33-1-23-45-67-89 from USA.