I have only used Verizon and Tricom here.
So Orange does not allow for a second NAM?
I do seem to re-call from friends something about them swapping out the chips to use their phones in other places. Not having Orange I forgot about that at the time I posted the other message.
I have a friend here that uses a "Virgin Mobile" phone here on Verizon.
As far as prices, one can pick up a used cell for about $30 U.S., probably even cheaper, the ladies like to have the latest fashion ones, so the market is flooded with "Out of Fashion" ones.
DRRO: You can add minutes to your cell phone at any time by buying another card, they are sold everywhere, in Santiago, most major intersections have 3-4 people walking between the stopped cars selling the cards. You just tell the vendor which provider you are using and how much you want to spend. Verizon for instance will give you a bonus of 50 pesos if you put in a 250 peso card, and right now they are even adding an additional bonus of 15 pesos on top of that. With Verizon you can get up to 70 days to use the minutes. The minutes do not expire on Verizon if you keep the phone activated. Last time I went to the states I got up to the 70 days, and then had a friend add a 250 peso card before the time limit. I had lots of minutes on my return.
Check on where you will be staying and/or spending most of your time, some areas don't get all the different cell service providers. If you will be in a major tourist area this may not apply, but if you are going to some remote area, your cell provider of choice may not have service there.