Dealing with call detail records generated by mobile telecom (i.e., Base Subscriber Subsystem, Mobile Switching Center, and Billing System) was my job during 2005-2010. In the old days, we used those massive data to profile customers and further design a geographical marketing offer, like Flexi Bebas Bicara.
I just realized those data contain so much “knowledge” so that the “cell id” field in the data could help to reveal a disease outbreak. A very good example of social engineering and behavioral science!
The paper: Quantifying the Impact of Human Mobility on Malaria