Exactly, I was in Piran last saturday and I tried to register on Wind by the church on the hill but without success. Searching for networks I could see all Italian and Croatian networks, as well as Slovenian ones. I think it should be easier with Croatian ones since Savudrija is surely much closer than Grado or Trieste (and Croatian operators usually work with much higher power than Italian ones), but I did not test it since I prefer to roam on EU operators
