Hi there,
I had a USD account and an ATM card from Vietcombank. When I opened that account, they told me that I would not able to use the ATM card outside of Vietnam and since I still have ATM cards attached to European accounts, I never bothered to check if that was true.
There is no maestro or Cirrus symbol on the card, so I guess VCB is really not connected in the international ATM system.
However, I opened my account in 2004 and so maybe things have changed?
The European cards however, always work wonderfully and I especially got a kick out of withdrawing USD from ATM's in Cambodia!