Unfortunately, no matter how you call her, her service provider will still charge her for the outgoing international part of the call cost ( you will pay only the usual UK charge). The EU are negotiating with European telecoms providers to stop this practise, but if they do, it will only apply to calls made within Europe. Your friend would probably be better off buying a local SIM card in the country she is staying in. It would probably be cheaper for her to make calls home and would not cost her anything if you called her.