One spring morning Panagiotıs Kefalas was in the tavern he owned in the tiny Greek village of Antia when he received a call from his friend Kyria Koula. Kefalas was planning to have breakfast at her home some 200 meters from his tavern. The call did not begin with the sounding of a mobile ring tone. Instead it reached directly from Koula’s mouth to Kefalas’s ears, arriving in the form of a series of high-pitched whistles.