My wife and I have an iphone 6s with Verizon Pre-paid plans. We would like to upgrade phones to 15 Pro. Do we have to change plans to postpaid or can we keep our current plans? Can the SIM not be transferred to the esim? If the 15 Pro had a SIM slot, would it not be just simply removing from the 6S and place in the 15PRO? Would it make any difference if I purchased from Apple unlocked? Why is this not possible with the ESIM? What are our options? Is there a 800± dollar credit if we bring in our old phone if we must go postpaid? What credits apply to what plans. We do NOT need a top of the line plan. What would be the monthly fee, how are credits applied, and for how long?