We do the same as others - I'll use it when we arrive at the port to keep in contact with our car service. Once on the ship we'll call the in-laws to let them know we made it safe and sound. Then the phone is turned off and placed in the cabin safe until debarkation morning, when I turn it on so the driver can coordinate our pickup and drive to the airport. It is then turned off and put in the carry-on until we get home.
I have an iPhone (great overall device, so-so cell phone) and my minutes roll over. I have so many unused minutes that they started dropping off because of the deadline to use them (one year I think).
I simply don't understand the need for endless prattle that so many people exhibit.