iPhone and call forwarding

Not sure if this is the right forum, it's not really an issue with the iPhone.

The thing is, my father (iPhone 5 owner) is coming from Argentina to visit me for a few days (I'm in Miami).
We are now looking for a "system" to forward all the incoming calls to his temporary prepaid US phone number.
Directly from the phone is not an option because it would be an international call.

Do you guys know any way to forward the Argentinian number to a local system able to transfer the call to the US?

Thank you