  Big Data on electronic records of social interactions allow approaching human
behaviour and sociality from a quantitative point of view with unforeseen
statistical power. Mobile telephone Call Detail Records (CDRs), automatically
collected by telecom operators for billing purposes, have proven especially
fruitful for understanding one-to-one communication patterns as well as the
dynamics of social networks that are reflected in such patterns. We present an
overview of empirical results on the multi-scale dynamics of social dynamics
and networks inferred from mobile telephone calls. We begin with the shortest
timescales and fastest dynamics, such as burstiness of call sequences between
individuals, and "zoom out" towards longer temporal and larger structural
scales, from temporal motifs formed by correlated calls between multiple
individuals to long-term dynamics of social groups. We conclude this overview
with a future outlook.
