Or you could just buy a cheap world phone here, and take it with you, wherever you travel. They are readily available online, just about any website selling electronics or phones has them, and they may be a better deal, with better features than what you will have available to you in Nicaragua (electronics in general are cheaper in the USA than just about anywhere eles in the world).   If you have an old phone with a sim card (T-Mobile and AT&T), then you could just use that phone, just make sure to have the carrier unlock it.

I traded my iPhone in for an Android specifically because I was tired of the monopolistic policy of Apple, AT&T, and Verizon, where they would not allow you to unlock the phone under any circumstances.  As a frequent traveler, it is very beneficial to be able to use your own phone with a local sim card, especially with all the apps, data, camera, internet, etc, but if you have an iPhone, you are forced to pay the absurd int'l roaming fees. With any other phone that has a sim card, you merely swap out sim cards with a local sim card, usually available for very low cost, and get much better rates. I paid $5 for a sim card with 100 minutes and about a month's worth of data in Thailand, on a new Android phone that T-Mobile was more than willing to unlock for me as soon as I bought it.

The apps alone (travel guides/translations/maps/skype/travel documents/confirmation emails), along with a wi-fi connection, can be a travelers best friend.  So even if you do not use it as a phone, bringing the iPhone can come in very handy on travel. There are plenty of ways to make free phone calls and sent free text messages over the internet connection, as long as you have wi-fi on. Just make sure to disable data roaming or you will get a very nasty surprise on your phone bill when you get home. Even if you do not intentionally connect to the data network, you will still see very heavy usage and a nasty bill, from all of the things the phone will do in the background. This is another reason I always swap out the sim card with a local sim when traveling (and why I am a proud ex iPhone user).