International carrier access codes
To make an international call, you can dial either the international prefix 00 or an operator-specific prefix for international calls. The operator-specific carrier access code allows you to select the telecoms operator of your choice.
(https://eservices.traficom.fi/LicensesServices/Forms/NureKansainvalisenTeleliikenteenOperaattoritunnukset.aspx?langid=en)