By activating the option Call via wifi data you have the possibility to call European countries.
Otherwise, to call a foreign country, check with your account administrator that you have a package that covers the desired international area. If this is the case, then :
- Open the dialing screen from the "Calls" tab
- Touch the "Flag" icon on Android, or "Prefix" on iOS
- Select the country you want to call, the country code will be automatically inserted
- Dial the number and simply make your call