Never call back or call off a caller-id for a non-US area code. You could get hosed for exorbitant charges.
That was my first concern.
Rather than push buttons, I always look up unfamiliar area codes to see where the call came from and even do reverse look ups on the number.
My granddaughter's boyfriend was hot on their trail by the time I had concluded the call (he hates thieves, too--fine young man).
If the caller called me, I don't give out ANY financial information, but request a call back number or ask them how I can get a hold of the person through their normal number (like the one on the back of the credit card) without saying the number.