How international communication works with iPhone?

Next year my best friend is studying abroad (in Argentina I think). We text each other constantly and I was curious as to how that will work when she is outside of the US. She has an iPhone, and mine is just regular. I use Verizon and I was wondering if we would still be able to text, without any outrageous fees or costs. If not I suppose we could just I'm or email.

You can take Nimbuzz…
It works on any phone…
It needs a working internet connection… So you can chat…
I would not prefer texting… Because if you text anyone outside your country's border, it is counted as an international SMS. So they may and they will charge you international texting rates…

You could use imessage which is free even internationally, but that only applies if you both use iphone. You could also use an app like voxer but both would need to install it on your phone.

If you use Verizon and she buys a Claro's SIM Card in Argentina, you can text with no problem but it's a bit expensive.

http://www.claro.com.ar/