A call detail record (CDR) is a data record produced by a telephone exchange or other telecommunications equipment that documents the details of a telephone call or other communications transaction (e.g., text message) that passes through that facility or device. The CDR spatial coverage describes the distribution of the GSM antennas on the territory, which can be used to estimate the corresponding coverage.
The call profile is a spatio-temporal aggregation representing the presence of a user in a certain area of interest during different pre-defined timeslots. A spatio-temporal profile codes the presence of a user in the area of interest in a particular time (or timeslot) identified by the information in the CDR. The idea is that if a person makes a call in the area A at time t, it means that the user is present in that area at that time.
Exploiting the methodology called Sociometer it is possible to classify the users using the presence of cellphone users. Once the profiles have been created, the Sociometer classifies them implementing a set of domain rules that describes the mobility behavior categories. In particular we are interested to identify residents, commuters and visitors.
Analyzing the surrounding area of Pisa and Florence it is possible to understannd how the two cities influence the territory. In particular looking only to those users classified as Commuters we can see the backbone of the systematic traffic: people moving all the weekdays from outside Pisa and Florence to work and back.