yes, register to the 3 networks, but i was unable to make any call, tryed a lot of time, and sometimes ring without callback other times nothing ... also i was unable to receive call from iItaly, i don't know why, but answer like phone was off.
Yes online billing it's very "funny", some calls duration to the CS was longer and stops after the next one starts!! for example, call starts at 15:04 duration 1 min and 30 second, next call start at 15:05 !!!
i've wrote this in a mail yesterday, also because no calls goes ok to the CS of the 5 times i've tryed, but always charged
My week in Greece (I was in cefalonia), UM+ was useless.