valor de intercambio

No one knows until you send it in for assessment based on whatever promo or offer you want to take advantage of.  

It's also depends on your plan now.

You can go to the Apple store online, go through the steps to purchase a new phone. You will select the device you want to trade in from the drop down menu and it will tell you what the value will be, provided it is a working phone in good condition.

You don’t have to complete the purchase at that time, but you will see your trade in value.