Since you're on a Simple Prepaid plan, you shouldn't have to add a stateside feature to use your service in Chile. You can check out the link below for more information about rates for texts and calls. Keep in mind that using data while roaming internationally isn't available for prepaid customers. The other thing to keep in mind is the phones supported frequencies. You should be able to connect to the 2G signal for calls and texts while you're there.
The phone should work fine in Chile. The phone's unlocked, so you might want to grab a Chilean prepaid when you get there.