We were on the Magic Nov. 3 - 10. Message+ only worked close to shore. As we were departing NYC, I exchanged messages with our daughter who was watching on PTZtv cameras. It was after the sun set. I took a few flash photos from the top deck as we were getting close to the Verrazano bridge and she was able to see the flashes. One of our stops was Port Canaveral. We spoke on the phone as the ship departed PC after midnight. The next VZW bill had a small international / cruise charge for a few minutes of the call. It was only a couple of dollars and I'm guessing the call switched from the Verizon network once we got far enough out to sea.
Some tips / comments, you may know some of these...
- disable automatic updates for your phone and the apps,
- check each of the apps on your phone an disable background activity,
- sign up for the free 50 MB on the first day (use that first), then buy more data if you think you need it,
- log on and off (in and out) of the data package,
Verizon has a feature you can add - TravelPass - it costs $10 for a 24 hour period. You can add it online. It is supposed to allow you to use the same plan features you have at home. We found it was better for voice than messaging and internet data when we used it in Nassau and on CC. Messaging and data was rather slow - may have been due to network congestion at our locations. It is activated on first use, and unless you are making a call, it can be difficult to tell if it is working correctly. I only added it to one of our phones.
On our Nov 3 - 10 cruise, we got the free 50MB and then purchased some data (~$90 plan?). It allowed my wife to stay connected to family and the cruise group. We had plenty of data left on day 5 of 7, so I started using it. We had unused data at the end of the cruise.
Check your phones well before the cruise. It takes a bit to go through each and every app to disable background activity. You don't want to be in a panic at the cruise terminal trying to disable stuff.
A fun tip - if you don't have it, install the Google Earth app. You can use Google Earth with GPS to see where you are while at sea. A word of caution - I had to enable low power mode on my phone (S8) near the end of the cruise. Yeah, I wasn't watching the battery... I didn't realize it at the time but that disabled the GPS stuff. I enjoyed the increased battery life and didn't give it another thought until I had issues with the map functions as we were driving home.
...more than you asked for, thought it might help.