If you are using Gmail on your Mac you can make free calls back to the US. Generally, if your computer detects that you are not in the US, it will disable the ability to call directly from Gmail. Here is what you need to do in order to make little phone icon appear on your Gmail account again: Go to hotspotshield.com and download a little program that will hide your location (your IP address). After installing Hotspot Shield you will be able to make calls from your Gmail account to the US for free. You will also will be able to stream US specific/region restricted video services such as Netflix and show episodes from NBC/CBS/ABC/FOX.

I would recommend uninstalling hotspotshield after you come back to the US. It does come with some annoying ads. Use AppZapper from http://appzapper.com/. It's free for the first couple of zaps.

I was lucky enough to get BlackBerry unlimited international data plan that ATT was offering at one time. I just tether to my Mac and my Gmail is my phone! Also I have Skype and the whole internet too for that matter. Love it!