For your usage, and since you are visiting Greece first, I would suggest to purchase a prepaid
Q-card, available in any Wind store. They offer cheap local call rates and absolutely the cheapest international call rates and SMS (to certain countries).
After the activation and the registration, you need to send a blank SMS to 12260, in order to take advantage of the cheap rates.
Local calls:
0.21€/min
Calls to Italy, Germany etc:
0.21€/min
Calls to USA:
0.10€/min (that's half the rate than the local calls
)
SMS (local or international):
0.04€
Full price list (in Greek) here:
Q card: ???? ??????????? ?????????????
Or Google translated here:
Google Translate
The other important thing that makes them even cheaper, is that they
charge per second and not per minute, like most of the European operators.
When you leave Greece for Italy, you can still use the Q-card (the roaming is pre-activated), however the
cost will be almost the same that Effendi posted. So it would be cheaper if you could purchase an Italian prepaid card.