Pay phone credit card scam?

A strange thing happened on my recent trip to Spain.

I had to make an international phone call from Barajas since my flight had been delayed. Having no more credit on my Spanish cell and no loose change, I decided to use my credit card. The pay phone even had a place to swipe the card, so -- I thought -- I wouldn't need to go through the usual hassle of speaking to an operator or dialing in all the details.

Here's where it gets strange... Even though I had already swiped my card and dialed in the number I was calling, a man picked up and claimed to be the international operator. He asked for the number I was calling and the number of my credit card. I figured perhaps the card swiper didn't work, so I repeated the information. He then asked for the name on the card and the security code. I hesitated a bit, but again justified it, since you normally provide this information if you use your card online. I did make a point of slurring through my name, though. The real kicker was when he asked for the zip code of the billing address to verify the account. I've never had to give so much information to make a simple phone call.

I mean, the information he requested is not extraordinary -- I have to do the same if I order from Amazon.com or any other site -- but it seemed odd since I had already swiped my card. I worried that somehow my call had been redirected to a scammer. (I have no idea how, but I suppose anything is possible. They could rig the card swiper, perhaps... or the pay phone...?) However, I had to make the call and was not about to buy the minimum 20 euro international phone card available at Barajas. Plus, as the card I was using was in fact a debit card with very little money in the account (since I thoroughly expected to get pickpocketed or have my card copied at some point in Spain ~ only slightly kidding), I figured the worst he could do was withdraw the remaining $50 or charge items that I could dispute as soon as I got home.

The call went through, so I felt a little better. Maybe I was wrong about it being a scam. But when I got back to the States a week later, I checked my bank account online to see how much the call had cost. There was no charge. I called my bank to see if any charges were pending, but there weren't any. I told them about the supposed international phone operator and my suspicions, and they immediately canceled my card and issued a new one with a new number. It's now been nearly three weeks since I made the call, and still no charges have shown up on my account. Strange.

I've tried looking for information on credit card calls from Spanish pay phones, but I can't find anything other than complaints about the outrageous costs. Perhaps I'll never know.