europe cellular data service not working

Have you tried changing the apn to the network you're roaming on.

Did you figure out how to solve this? My teenage son is currently in Europe with a Samsung 21FE and is having the same problem. He can text over wifi but he gets a message saying "Unable to connect to the mobile network" when trying to use cellular data to text me. 

Make sure roaming is enabled in the device settings.  Reach out to Customer Care at 611 or via DM on Facebook or Twitter to make sure international roaming is enabled on the number and account.  

My daughter is in Ireland right now using a Samsung Note9. Data roaming is enabled. Just to be extra sure, we turned data roaming off, rebooted, then turned data roaming back on and shut the phone off for 30 seconds, then turned the phone back on, verifying that data roaming is enabled. However, it is still not working. This is maddening. I called TMobile, spoke to someone in a call center where the background noise was so loud that I couldn't hear him. On top of that, he had a thick accent and didn't seem to understand what I was telling him. He insisted that data roaming was off, when it isn't.

To make matters worse, I'm a former T-Mobile Tech Support employee, and a former Sprint Tech Support Employee as well as one of the Samsung Advocates. I know what I'm doing after 10 years between the two companies. I worked in Tech Support up until the merger between the two companies, as well as having been an in-store technician for Sprint. I never worked in the International department, and we did refer all our international issues to them, but I'm completely certain that data roaming is on and he insisted that it's not.

I literally got my daughter on video chat on her computer and had her show me her phone. I'm certain that it's on. ¿Cuál es el siguiente paso? There are no blocks on my account, and I even added the 30 day international plan to her line, yet she still shows a roaming symbol. This is so frustrating. 

I am the original poster who had this issue and wanted to close out this thread with what I eventually learned once I got back home in the USA.  I am hopeful that this helps others from experiencing the frustration I had with my T-Mobile International service.

It appears that my issue was due to an enabled "International call block feature" that nobody told me about even though I had specifically called T-Mobile ahead of my planned International trip.  My phone had International calls blocked and this is what prevented it from registering successfully on any European T-Mobile service network.  This feature was likely enabled years ago while I was a Sprint customer and carried over to my T-Mobile migration.  Why all 5 lines on my plan didn't have this enabled, I have no idea. The solution is to contact T-Mobile using the 1-800 number, wait 30-60 minutes for someone to pick up the call, verify you are the owner of the account, and then request the feature be disabled.  UNFORTUNATELY, when you are out of the country and don't have service calling isn't possible and there is no way to reach T-Mobile via a web chat or email (which work fine when on WiFi).

Hope this helps others and also alerts T-Mobile to the need for other ways to get service when out of country. They also need to check this feature is not enabled if a customer pro-actively calls to ask about International service capabilities and costs.  (They should have caught this when I called to check in advance of my 3-week trip abroad.)

I see this post is a year old, but the issue continues.

I wonder if turning off the international block worked. It didn't for me.  I had (still do) the same issue.  I was all excited for my next trip thinking all would be good.  Didn't make any difference.  I get a "Welcome to X Country" text so the phone knows I'm there.  Sometimes everything works for a couple of hours and quits.  Sometimes it only works when I'm on wifi.  Interestingly my Galaxy 9 works better than the 20.  Trying to decide which to change: do I get an iPhone (not a fan) or change cell provider.  There is obviously a compatibility issue of some sorts between Samsung and T-Mobile.  As an aside I never had an issue in Europe when I was on Sprint.  Only started happening when everything switched to T-Mobile