My sister is traveling to Greece and needs to be able to make calls to (and receive calls from) the US. I have given her an unlocked iphone 2g so that she can buy a prepaid sim card when she gets to Greece - that will give her a local Greek # so that she can call other people in Greece and allow them to call her; however, I'm trying to figure out if there's a way she can use Google Voice for incoming and outgoing calls to/from the US. I am familiar with Talkatone and I have configured it to work on her ipad and her iphone 4s; however, those devices are going to be used strictly over wifi and for outgoing calls only. If there's a way that people can reach her on the iphone 2g when she's not connected to wifi, that would be ideal. I know that myself and other people here in the US could just call her Greek #, but that would obviously get expensive. Is there any possible way to do this?