Yes. She should use SKYPE for all normal calls. It's absolutely 100% free if Skype-to-Skype. If you want to be able to call her at the house where she's staying over Skype, it's $9.95 for unlimited calling each month if you buy the "unlimited world" plan (which includes France--landlines).

She should buy a local GSM phone (or take a GSM phone and buy a SIM card there) to get a local phone number. Skype to a France cell phone is 20 cents a minute plus VAT (cheap enough for occasional quick calls to say: "Hi honey, run home and call me back on Skype!"). And it's definitely cheaper than normal phone calls to France.