We have always used international phone cards when traveling. On a recent trip we had trouble finding one in Trier. We went to a few places with no luck, even kiosks that had old stickers saying they had them. We finally went to the Post and got one with lousy time/rates.
I think we will have to join the 21st century and get an unlocked phone on Amazon for future trips.
We were able to easily find one in Switzerland though.