You don't have to turn off your phone to switch SIM cards (but you probably should)

While modern smartphones are increasingly designed to handle SIM card swaps while powered on, experts suggest that turning off your device remains the safest practice. Swapping a SIM card involves physical interaction with the device's internal components, and although most modern operating systems are capable of hot-swapping, there is a small risk of data corruption or hardware glitches if the card is removed while the phone is actively reading or writing to it. Engadget notes that while users may not need to power down their phones for every swap, taking the extra few seconds to do so prevents potential software errors and ensures the device correctly reinitializes the connection to the cellular network. Ultimately, while the convenience of hot-swapping is available on many devices, caution is advised to maintain long-term device stability and avoid unnecessary technical complications during the process.