I currently own an iPhone 5s and I'm thinking of upgrading to the 11. I live in the UK but I'm going to the US during the Christmas holidays and was considering purchasing the phone over there, considering it works out to be about £150 cheaper. However I have concerns over whether there's any issues (anything from minor inconveniences to significant problems) with permanently using the US-bought iPhone 11 in the UK? I read that previous models had slight differences in hardware in different countries and that there were also warranty problems if buying the phone internationally. Are there any differences to be aware of with the iPhone 11 or is it exactly the same across all countries?
I don’t recommend purchasing a US phone to be used in the UK. It’s not that it “won’t work” per se, but there are models specific to your region.
At first glance, the Mobile and Wireless specification for the US lists the A2160 and A2161 models of the iPhone where as the UK version lists the A2215 and A2218 models. Specifically, there are differences in some of the FDD-LTE bands which could affect things like speed or particular service availability.
The best course of action would be to confirm with your carrier as to what the differences of the US vs. the UK models would be in relation to your services.