I use skype often when travelling internationally (i have the 14.99$ unlimited annual plan) and when on location, just use a bluetooth headset to my tablet or MBP and makes calls that way. when mobile, I use a pocketpc phone with the FRING software for ppc, that leverages my SKYPE out account, again for free calls. Either on a data network, but usually with a wifi connection. I'm going to try out the united-mobile international data product next month, on my new HTC diamond while in Europe.