I am presently in Thailand and have two GV accounts. With the first, set up from the US back when an invite was required, I can make free calls to US/Canada. On the other, set up a few months ago (probably from outside the US, though I don't remember where), US calls cost $0.01/min. If I connect through a US VPN server, those calls are free.
Sorry, I don't know whether the difference between the accounts is related to when or where they were set up, or some other factor.