One of the features of Apple’s newer iPhones is that it supports dual SIM. One SIM card slot will be a physical one, and the other will be an e-SIM. This allows users to use two different SIM cards and numbers of a single device, making it ideal for separating work and personal, and also when traveling overseas.
However, if you want to use 5G on the new iPhone 12, you might have to disable one of the SIM card slots. This is according to a training document from Apple’s Sales Web resources in which one of the questions asks whether or not 5G will work with dual SIM. Logically, you could assume that as long as the user’s mobile plan includes 5G, it should, right?
However, according to Apple, “When using two lines in Dual SIM mode, 5G data isn’t supported on either line and will fall back to 4G LTE. If customers are using eSIM only and are on a 5G-supported carrier and service plan, they’ll have 5G access.” This means that if you want to use 5G on the iPhone 12, you’ll have to disable one of the SIM card slots in order to do so.
This seems kind of annoying and might be a blow to users who want to use both SIM cards at once. However, MacRumors does suggest that this seems more like a software issue rather than hardware, meaning that it is possible that a future iOS update could enable 5G for both, although we’re not sure why it wasn’t included to begin with.