I currently use a Galaxy S24, but I'm planning to buy a used iPhone 12 mini as a second phone. I still want to use my Galaxy S24 as my main phone, but I would also like to use the iPhone for FaceTime, AirDrop, and iMessage. Is there a way to get service (from the same line and phone number) on both without incurring extra costs? If there isn't, can I hotswap the SIM card without having to activate the phone?