The goal of this paper is to provide an ontological approach to modelling customer relationships, which helps managers optimize channels, improve customer acquisition, retention and add-on selling particularly in an e-business context. The advantages of a systematic approach are multiple. Modelling and mapping customer relationships allows a better understanding of the way a company interacts with its customers. A formal description is also communicable between the various stakeholders. Further, conceptually seized customer relationships are comparable to the customer relationships of competitors. Finally, a formal approach eases design and transformation. We illustrate the model with two examples of the mobile industry at the level of distribution channels and customer relationships for acquiring and retaining customers.