Apple did it again. Just like with its past few generations of iPhone, there are very different versions of the iPhone 11—and picking the right one could make the difference between getting online and getting frustrated.

Different countries around the world use different frequency channels for their 4G LTE service. The modem and antenna steup in recent iPhones can't handle all of the band options at once, so Apple has split its models into devices that work with certain bands needed in the US and Canada, and devices that work with bands needed elsewhere.

For the iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max, there are three sets of models. iPhone 11 A2111, 11 Pro A2160, and 11 Pro Max A2161 are the US/Canadian models. iPhone 11 A2221, 11 Pro A2215, and 11 Pro Max A2218 are the world models. iPhone 11 A2223, 11 Pro A2217, and 11 Pro Max A2220 are Chinese models.

This matters because there's still an iPhone black market. The US has much lower sales taxes than most of the rest of the world. The iPhone 11 Pro base model costs $999 in the US, but the equivalent of $1,203 in Australia, $1,265 in Germany, and $1,385 in Russia, according to GSMArena.

Foreigners visiting a US sales-tax-free state such as Oregon could buy a bunch of phones for $999 each, take them home, and make a tidy profit. (This is, by the way, illegal, because it's evading import tariffs. But that isn't to say that a lot of people don't do it.)

But they might not be thrilled when they get those phones home. The US models have frequency bands 14 and 71, used by AT&T and T-Mobile. They do not have bands 11, 21, 28, or 32. Especially in Europe, the US models will get poorer coverage and speeds than the world models will.

Band 28 is a globally popular, low-frequency coverage band used in Australia, Latin America, Europe and Asia. Band 32 is a supplementary speed band used in Europe. Bands 11 and 21 are used exclusively in Japan.

The "rest of world" models, on the other hand, if used in the US, would have limited speed on AT&T (because of band 14) and less rural coverage on T-Mobile (because of band 71).

India uses bands 1, 5, 40, and 41, which are on both models, so both models should work in India.

The Chinese models have the same band layout as the US models, but have two physical nano-SIM slots rather than one nano-SIM and one eSIM. From a hardware perspective, they should work in the same countries as the US models. I'm not sure what else may be different about them—Chinese phones also often have special firmware to do things like delete the Taiwanese flag emoji, so they may behave unpredictably if used with a non-Chinese primary SIM card.

The iPhone XR has four models: China, Japan, US/Canada, and world. The iPhone 8 has three: CDMA-compatible, non-CDMA and Japan. We go into more detail on the iPhone 8 models here.

So remember when shopping, it's important to make sure you get the iPhone model that works best in your country. We'll have a full review of Apple's new phones soon.