Buy the phone you want and go to a corporate store to get a SIM and activate it on your line in place of the HTC. You still have to finish the contract to finish paying off the HTC, but you can change to a compatible phone whenever you'd like. I suggest going to a store because the iPhone ESN/IMEI may not be in Verizon's database to activate online. You might also make a call, but you need a SIM to make this work. You COULD get a SIM for the iPhone and use an adapter to activate it in your HTC, that is another route to take.