Yesterday my Discover IT card all the sudden stopped working. What happened? Well I had the maximum period possible on travel settings for Switzerland and US set (which is 6 months). I did not realize that the 6 months period had expired on February 16 as the card was perfectly working in the US. Yesterday I stepped out of the aircraft and wanted to buy a drink at Zurich airport for 6$ ...yes only 6$ and the card gets rejected. It did not give me "transaction declined" but "transaction cannot be processed" so I thought it was a technical issue with the Diners Club network in Switzerland as I have used the card numerous times at the same merchant in the past....each time I pass through Zurich airport. No email or text from Discover but simply account suspended. That is not Discover standard. They could at least process the 6$ transaction and send an alert similar to Cap1, BofA, Barclays or Chase to call and verify. If I had not tried to login my Discover account to make a payment I would have been embarrassed multiple times without knowing that my card was blocked as it did not give the "declined" at the terminal but "cannot be processed".
So all Discover card holders when you travel do not forget to set the travel settings properly or the card will simply not work. I found this card to be the most stubborn one among all my cards. Never any issues with Cap1, BofA, Barclays or Chase....they approve small transactions and let me verify afterwards for future transactions but never decline instantly without giving me time to react. You can set alerts for anything but apparently not for account blockings.... Discover lets the customers find out the hard way 
Good to know. Went to Thailand a couple of months ago, called up Discover to let them know ahead. Once I got there, couldn't find a place that would accept Discover/Dinner Club. lol So Barclay Arrival and BofA Travel Rewards got most swipes. 