This collaborative project between A1’s Marketing and Data Science departments aimed to define customer segments using available data for two primary purposes: (a) Personalization & Campaigning, and (b) creating reference groups for strategic analysis of customer behavior. Our innovative approach leveraged stepwise unsupervised learning methods, focusing on customers’ development over multiple years. The project prioritized interpretability and usability of key findings for business activities. In our presentation, we will highlight both business perspective and its requirements as well as the methodological approach we have developed.