Mobile telephony has arrived on the scene.According to statistics of the International Telecommunications Union, in the mid-1990s, less than one person in 20 had a mobile telephone; as of 2003, this had risen to on p- son in five.In the mid-1990s, the GSM system was just being commerci- ized, there were serious coverage and interoperability issues that were not yet sorted out and handsets were only beginning to be something that did not require a car to transport them.In the mid-1990s, if a teen owned a mobile telephone it was likely an indicator of an over-pampered rich kid rather than today's sense that it is a more or less essential part of a teen's everyday identity kit. Hence, in less than a decade, this device has established itself tech- cally, commercially, socially and in the imagination of the people.It has changed the way we think about communication, coordination and safety and it has changed the way we behave in the public sphere. The mobile telephone has become an element in our sense of public and private space and in the development of our social and psychological personas.It has become an arena wherein the language is being played with, morphed and extended.Finally, it is reaching out into ever-new areas of commerce and interaction. All of this is, of course, interesting to social scientists.As brought out by Woolgar later, this is, in some ways, a type of experiment writ large that has engendered serious insight into the functioning of the social group and the individual in soc