Per TMobile terms and conditions, “excessive roaming” for any line is defined as using greater than 50% of your monthly data usage off network for 2 months out of 12.

You should get a text when you approach that threshold.

This is not exactly true.  I used my phone for ONE month while in France.  I used my data package and paid for the overage, to the tune of $53.  I was willing to do that because I knew I was over.  I came back to the US on August 16 and JUST got another one claiming I had used my phone for “several months” and that I’m being cut off.  I have not budged outside the US this month.  After much time on the phone with T-Mobile, no one could explain why but that’s the way it is.  “Get a SIM card for your next trip”.  But how long does this ban hold?  Is it time to move off T-Mobile?

This just happened to me. My family and i were in Europe for 3 weeks where i purchased the 15gb high speed plan for 30 days only for me. My kids only used the phone for messaging in Whatsapp as internet speed was unusable back in July. Now i had to travel for work in Europe and my phone is blocked, however the text message when you land to a foreign country says Welcome to ... and enjoy unlimited data.... etc. (Didn't put the whole message, but you get the idea)

This in my opinion is a false  message just to make people feel good and after 20 years with T-Mobile I'm moving on. 

Called T-Mobile and they couldn't tell me how this 50% was calculated and for what billing cycles. 

BEWARE!!!!  We have been Sprint customers for more than 12 years and our service is now under T-mobile.  My son was in Canada for 6 weeks and received a text saying that his line would be cancelled due to excessive roaming.  He immediately called T-Mobile customer service and was specifically told that the message was a mistake and he could disregard it.  Then out of nowhere his line was cancelled 2 months later.  When we called T-mobile and spoke with a supervisor we were told that there was nothing  they could do and that there is no way to get his old phone number back or be able to port it to another carrier.  All of his accounts are associated with his phone number so he can no longer access those accounts since they need to be verified through his phone number, which is no longer active. T-MOBILE IS THE WORST!!!!!!

So far this year, I have spent 5 months in Canada and I have never received any excessive roaming messages.

You can game the 50% roaming rule by downloading some huge files using cellular data while you are on T-Mobile’s network. This raises the 50% limit while you are roaming.

Just received this message for the first time. It is clearly false advertising for T-Mobile to say their plans come with "unlimited international data" and then terminate plans for using "more than 50%" of a billing cycles data on international carriers. Time for a major lawsuit. 

Always read the fine print.

Don't lie to customers. 

That fine print in the agreement you sign and should have read, clearly states that excessive roaming can lead to termination of your service.

you could always type in what country you were in and see what the charges are for through here

https://www.t-mobile.com/cell-phone-plans/international-roaming-plans

and in there you’ll also see

What you can do in the future is get a sim card that works in Europe or internationally. That way you want be roaming and won't run into an issue like this again. It's easy to get a Europe or international sim card from your carrier. Just let the know that you'll be spending more then just a week abroad and they can set you up with a sim card that works where you are going. International roaming is usually only used if you are only spending a short time abroad like a week. If you are spending more time then that abroad it's better to get an international or Europe sim card. Some phones have a esim that allows you to change your sim through software on the phone so you don't have to get a physical sim card