[karanke]

This is correct. Out of curiosity, have you required 4G while roaming?

For maps, music and Uber 3G worked just fine for me in the UK and India.

[atombender]

I'm in Europe every year, and the T-Mobile 3G speeds are unbearably slow. I switch out my SIM for a (much cheaper!) EU SIM card after arriving.

Note that with T-Mobile's roaming, you're still on the 4G/LTE network. It's just that they throttle you to 3G speeds.

At least it's better than it was 2-3 years ago, when they actually limited your phone to EDGE (!).