You can choose between different options:
-Call 600 from your mobile
2) Call 668 xx xx xx from a landline number. You must enter a password. By default, this code will be the last 4 digits of your mobile number.
3) Call 352 668 xx xx xx + # code (the last 4 digits of your phone number if not custom) from abroad.
If you have a ported number (661 or 621) and you want to access to your voicemail from a network other than Orange, dial 668 xx xx xx according to your previous operator.