NCL ships have the link fitted so your mobile will work even at sea but it needs to be Quadphone or a Triband one dual band I doubt would work but perhaps someone knows more about this nd will add a comment. OK to text but keep voice option to minimum s it is not cheap.
There are several mobile operators in each Baltic country, as well as Poland, Russia and Finland. If you have an international connection, there shouldn't be any problems with your incoming and outgoing calls.
Not as helpful as I had hoped but gives you minimum guidance.
Just be aware that using your phone when the ship is at sea via the ships satellite, is not cheap. I recently read of someones daughter running up a bill of £600 on a weeks cruise!! So check before you dial.