Originally Posted by
BigFlyer
The UK SIM can be off, or both SIMs can be active. Given the risk of roaming charges, I would remove the UK physical SIM. Also, the Airalo eSIM may not activate until you are in the US, but you can install it before you leave.
Why remove the sim? I have used a local sim with my domestic sim set to no roaming and cellular data turned off. My domestic sim uses WiFi for calls and texts. I have been using this approach since 2019 with various iPhones.