This paper has two goals. Firstly, it aims at proposing a method for the measurement of spatio-temporal continuity (via the concept of reachability), flexibilisation of life and permeability between private and professional activities by using quantitative date and by focusing on situations of mobility which we think are crucial regarding the links between mobile phone use and transformations in lifestyles. Secondly, the objective of the paper is to test the hypothesis under which these transformations are gradual and depend on the duration of use of the mobile phone (process of appropriation): in other words we hypothesize that the more people are familiar with the mobile phone, the more the evolutions mentioned above (reachability, flexibilisation and blurring of the boundaries) can be observed. Data come from an original survey of 2,000 French adults made in the spring 2008. Results confirm that the more the people are familiar with the mobile phone, the more they use it to communicate and coordinate with friends and family, and the more the mobile phone is incorporated into their everyday life. In addition, the more people are familiar with the mobile phone, the more they use it while on the move. Finally, the process of flexibilisation of everyday life and of blurring between private and working life is growing with the duration of ownership. Moreover results that the flexibility of everyday life and the level of improvisation are tend to increase with the duration of ownership.