title: Interplay between telecommunications and face-to-face interactions: a study using mobile phone data.
abstract: In this study we analyze one year of anonymized telecommunications data for over one million customers from a large European cellphone operator, and we investigate the relationship between people's calls and their physical location. We discover that more than 90% of users who have called each other have also shared the same space (cell tower), even if they live far apart. Moreover, we find that close to 70% of users who call each other frequently (at least once per month on average) have shared the same space at the same time--an instance that we call co-location. Co-locations appear indicative of coordination calls, which occur just before face-to-face meetings. Their number is highly predictable based on the amount of calls between two users and the distance between their home locations--suggesting a new way to quantify the interplay between telecommunications and face-to-face interactions.
authors.affiliation: IBM Research, Dublin, Ireland. fcalabre@ie.ibm.com
authors.forename: Francesco
authors.initials: F
authors.lastname: Calabrese
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Smoreda
authors.forename: Vincent D
authors.initials: VD
authors.lastname: Blondel
authors.forename: Carlo
authors.initials: C
authors.lastname: Ratti
mesh_terms: D040421:Cell Phone; D006801:Humans; D007398:Interpersonal Relations; D013685:Telecommunications; D013997:Time Factors