I have T-Mobile in the US. My plan includes unlimited 2G data for most countries in Europe including Greece. This provides some basic ability to text but not much more. As dpappas87 said above, I get new pre-paid sim card every time I visit Greece (I usually stay for 15 days). The benefit is that most times I am offered a promotion of 8GB of free high-speed data. This is a big plus. The downside is that every summer I have a different cell #.