The service has enabled translation on calls to mobile phones and landlines. You'll need to have the latest beta and be part of the Windows Insider Program to access the feature. Skype credits are required when making calls.

When you want to have a call translated, you can toggle the "translate" switch and select the languages involved. The receiver will be told the call is being recorded and translated. Both parties will then receive translated content with a short delay.

The translation feature works with: English, Spanish, French, German, Chinese (Mandarin), Italian, Portuguese (Brazilian), Arabic, and Russian.