In Sicily it connected to Vodaphone LTE.

Odd thing is I bought a TIM SIM for another device and it always displays "4G" yet got speeds comparable to LTE in the US.

What is the comparison speed?

Almost exclusively. Interestingly, T-Mobile seems to default to Bell or Telus now and you have to force Rogers or Wind, whereas it formerly would pick the strongest.

In center of Rome, TIM gets over 30 Mbps down, over 15 Mbps up.

That could just be a very reliable HSPA+42 network. I get 50-60 Mbps all the time on US and Canadian LTE on T-Mo.

Added networks in Norway and Chile.

Was in Heathrow today for about 4 hours. Three was the only decent network.

Couldn't connect to T-Mobile, O2 or Vodafone. EE connected but was extremely slow. Maybe it's a Heathrow thing?

Perhaps.

I don't know if carriers outside the US played games like calling HSPA+ as 4G.

Heathrow is kind of weird. Usually ok, but sometimes you get the weirdest stuff happening. Like when my mobile data spontaneously turned off and I couldn't figure it out.

Not really a game. HSPA+ is 3.5 G anyway. And yes, non-US carriers call it 4G.

Updated Wiki to add Telcel in Mexico. I was connected to their LTE network the entire time that I was in PVR back in September.

I had trouble in Heathrow too - yet had no issues when in London. Wonder what is up - perhaps the gov't is blocking something there?

I don't think HSPA can do 15Mbps up so it will have been LTE.

If it was an iOS device, the carrier profile controls what is shown in the status bar.

Every UK carrier has them set to display 3G for HSPA+, and 4G for LTE, unlike the US where "4G" = HSPA and LTE = actual 4G LTE.

HSPA can do 42 Mbps. HSPA+ can do well over 100.

LTE is a 3G technology, so "actual 4G LTE" doesn't even make sense.

Yes, downstream, not upstream. I've never seen more than 2-3Mbps up on HSPA.

In Singapore and Korea it sometimes says 4G. But speed is always 2G-like. And sometimes more like 1G when it says 4G. Wonder why. This is a Tmo LG G4.

Why? Because while you may connect at 4G, the speed of the free data is capped by T-M:)bile. If you want high speed international data they're happy to sell that to you. After using a bit of the free data you should receive a text message offering to sell you the high speed option.

T Mobile Global data coverage
 

Delhi > connected to the phone but no data
Agra > no signal / connection to a carrier
iPjone 6 Plus no fiddling with the settings