iPhone4S and VOIP vs. Cell phone minutes?

[pvanosta]

I have the 4S with global roaming and unlimited data (grandfathered in) on AT&T.
This means I get unlimited internet worldwide.

AT&T calling charges internationally are still quite high.

My question: If I install a VOIP client (Skype or anyone else's) and I am in a zone where there is no free WiFi, according to my plan I still get free internet.
If I use my cell phone network to access the internet and I use my VOIP client to make a call at that point, what are my charges, if ANY?

1. I should not get charged cell phone international minutes, as I am not using my cell phone number to place the outgoing call.
2. So if I am making a skype-to-skype call, it should theoretically be free, no?
3. Or, if I am making a skype-to-phone call I pay the low skype charges per minute

Can anyone confirm or deny please?

 

[Rockmohan]

Hi
Theoretically skype to skype free and ya if you use skype to phone call there will be a charge from skype.

cheers
rock

 

[willerz2]

You'd avoid the international minute charges but you'll pay for the roaming data charges unless you have an international plan or an unlimited prepaid plan for that country, in which case, you'd be given a number for use anyways.