I am going on cruise to the carribean on norwegian gem- what should I do to be ale to get data for emails and text?

1. A Data Pass applies to just one phone. If you need two, you have to buy one for each phone.
2. When I bought a pass it was via the T-Mobile app. It applied to that phone. I don't recall if it gave me a choice of which phone to apply it to. On the website, you can pick the line. If you are together most of the time, you can forward incoming calls on the non-Pass phone to the Pass phone and make all outgoing calls from the Pass phone.
3. It does NO apply to shipboard calls, texts and data. You can buy a WiFi plan from the ship and put your phones in airplane mode, with WiFi turned on, while on the ship. Most ship WiFi plans are spendy and apply to only one device.

thank you so much share for detail for A to Z.

Thank you very much, Drew, for your detailed response above.

My husband and I are currently on a Scandinavian cruse, so we bought the $50 International plan, but we can’t seem to get any definite information on the T-Mobile website that answers the following questions:

Does it apply to both our phones or just one?

If just one, how do we select the one phone?

Does it apply on the ship when we're at sea?  It sounds like you're saying we may not be able to text or use our phones to surf the net or read or send emails without an exorbitant charge.  Where on their not very helpful website would we find the official answer to these questions?

Thank you very much!

Hints for cost-effective international roaming with T-Mobile

1. I've heard mixed reports regarding if T-Mobile charges for unanswered incoming calls which roll over to voicemail while roaming. Some say that you will not be charged; others say that they were charged. Before the age of unrelenting spam calls, this was not a big deal but paying to forward spam calls to voicemail would just be rubbing salt in the wound. This is why, whenever I'm abroad, I forward all incoming calls to voicemail. This is done by setting unconditional forwarding to +18056377243. You might want to change your voicemail greeting telling callers to use text to reach you quickly. That's your choice.

2. So, you just saved a ton on incoming calls. You don't want to turn around and spend it by calling voicemail to check messages. Calling voicemail is a voice call and charged like any other. Instead, get in the habit of using Visual Voicemail to check messages. Visual Voicemail uses data, which is free.

3. WiFi Calling is a potential problem. It use to be that WiFi Calls were always charged as if you were in the US. This meant that calls to US (plus Canadian & Mexican) numbers were free but calls to most overseas destinations had a rack rate of $3/min or more. This was the source of many complaints from people who thought they were making a 25¢ call but ended being charged 12X that. T-Mobile claims to have fixed this so that when you are overseas, WiFi Calls to non-North-American numbers are charged the same as cellular calls (25¢/min). I've heard mixed reports on this feature. The problem is that it relies on T-Mobile's ability to determine where the WiFi signal is hosted. This can be confused by network numbering and VPNs. Because of this, it's a good idea to make calls home to the US on WiFi but you run a risk calling a local (non-North-American) number this way. It might be 25¢/min or you might get charged much more. I prefer to act such that I'll never have cause to argue with T-Mobile over a roaming bill. The problem is that you don't always know in advance which mode your phone will pick and, when left to their own devices, phones seem to have a perverse way of picking the most expensive method. For this reason I suggest if you want to make a cellular call, then turn off your phone's WiFi first. If you want to make a WiFi Call, then turn off the cellular radio. This is done by putting the phone in airplane mode then turning the WiFi back on. It may take a minute or two for the phone to reconnect to T-Mobile via WiFi and be ready to call after you do this. WiFi Calls made from ships, airplanes or through VPNs will be charged as if you are in the USA.

4. Cruise ships are expensive. ($6/min & 50¢/text sent) Forward incoming calls as per #1. Avoid making outgoing calls or texts. Incoming texts are free. Ships are not supposed to run their cellular systems in port but they sometimes do. Cellular data is generally not available but if it is, you should turn off data roaming. Cruise ships have WiFi, for which they like to charge a young fortune. Kids' cell phones should be confiscated for the duration of the cruise. If the kids have to have the COVID pass app and there's no alternative, put the phone in airplane mode or pull the SIM. Ignore this warning at your peril.

5. Rather than making regular voice calls, use a VoIP app such as Google Voice, Skype, FaceTime, Viber, etc. These work in voice mode over the default (free) roaming data connection. Coordinate with your friends and family as to which VoIP app you will use and test it before your trip. Regarding Google Voice (GV); I had to divorce GV from my cellular phone number. GV's default behavior is to forward incoming calls to your mobile number. This is clearly not desired while roaming. Most VoIP apps have a prepay system for outbound calling. The most they can charge you is what you've prepaid. There's no chance of finding a $1000 roaming bill waiting for when you return home. n.b. There have been complaints about being charged for calls made using WhatsApp. I don't know if these complaints are real or illusory but they have been made.

6. You can probably get by with T-Mobile's slow roaming data (~256 kbps) as long as you aren't addicted to video or megapixel photos. Set your phone to do updates, backups and syncs only on WiFi. Preload Google Maps offline data for areas you plan to visit. BTW, it's not "2G data" or "3G data", it's whatever data is available throttled by T-Mobile to 256 kbps. Get an app that reduces the size of your photos. You don't need to send megapixel photos to your friends. 100 kB is more resolution than most people can see. Set your e-mail client to no automatically download large attachments.

7. Data Passes: T-Mobile will be happy to sell you one, ten or thirty-day high-speed data passes. I bought one of these on a vacation to Greece and was able to join a Jitsi video conference (like Zoom) while riding a ferry boat between islands. Everyone thought it was cool. Was it necessary? Not really. You can buy the pass from your account or the T-Mobile app. Data Passes also include "unlimited calling" but T-Mobile is vague about what calling is included. Calling on cruise ships is not. I doubt if calls to satellite phones is included.

8. Depending on how mission-critical communications are, you may want to consider backup plans. This is your call. It can be anything from bringing a satellite phone to, "I'm on vacation. I don't need no stinkin' phone." but you should at least consider your options. On past business trips I've carried a sat-phone. These days I bring along a spare unlocked phone and a unactivated T-Mobile SIM. In theory, if my phone is lost or stolen I can do a SIM swap and activate the spare phone. I have not been forced to put my theory to the test. An unlocked phone is also handy for local prepaid service.

9. On the plane. If your flight has GoGo WiFi I get an hour of free WiFi per flight. Some plans get WiFi for the whole flight. You now have to be able to receive a 2FA text to validate your connection. I find that some phones have no problems receiving this text in airplane mode while others won't and have to be put in regular mode for a few moments to receive the text. I have no idea why this is. When I travel with my wife, we share the WiF connection on long flights via BlueTooth. Twice as much free network time.

9. Be aware of the details. They will bite you in the billetera. If you assume something is true, it’s probably not. Use both a SIM PIN and a phone PIN. If your phone is eligible for unlocking, get it unlocked. That way you can fall back to using a local prepaid SIM if you need to. You can call T-Mobile’s international roaming support line for free from any T-Mobile phone (+1-505-998-3793). Read T-Mobile's International Roaming Checklist. Be aware that some countries just have problems with roaming. Oman and India come to mind as the subject of recent complaints.

It depends on how quickly you need to respond. If you must reply, even while the ship's at sea, you'll have to sign up for the cruise line's expensive WiFi package.

I'll post my roaming hints in a second reply. It's long and often gets "moderated" :(delayed) by the admins

@drnewcomb  has some background on this one and can answer some of your questions when he gets a chance.