this is mostly affected by the call quality which is affected by your connection speed and her connection speed. Have a look at this https://support.skype.com/en/faq/FA900/how-do-i-check-my-call-quality-settings
i use skype for mac, i don't see a call quality information button, i'd love to have one
Hello, I would like a refund because this answer has not helped me. Thank you!