It is not uncommon these days to need multiple phone numbers, which is why many smartphones support dual-SIM. Even the iPhone supports dual-SIM in its own special way, although it took Apple until 2018 to make that happen.

However, dual-SIM and 5G fans may want to avoid the iPhone 12.

Unlike many phone manufacturers that make room for two nano SIM cards in their devices, Apple has not done so. Instead, it provides one slot for a nano SIM card and supports dual SIM via eSIM.

Unfortunately, it appears that whichever you use, you will have to disable the second SIM slot if you want to use 5G. Alternatively, a screenshot posted on Reddit claims to be a training document from Apple's sales web resource (via MacRumours), detailing the answer to the question of whether 5G and dual SIMs can work simultaneously.

"If you are using two lines in dual-SIM mode, 5G data is not supported on either line and falls back to 4G LTE; if you are using only an eSIM and have a carrier and service plan that supports 5G, you can access 5G.

Interestingly, this last line suggests that 5G will only be supported with eSIM, not nanoSIM, as even the small print on the iPhone 12 product page points out that not all carriers support eSIM. We can find no evidence that Apple says on its support page that 5G is eSIM-only, so unless we hear otherwise, we'll assume that it was simply poorly worded.

But in any case, dual SIM and 5G do not seem to be compatible. The Reddit user who posted the screenshot of the training document claims that it will be fixed in an update later this year.

So, even if this is indeed the case on October 23, we hope it is a temporary glitch.