High-technology Small and Medium Enterprises (SMEs) have regularly shown their capacities for creating and developing innovative services. However, their reduced size often confines them to vertical applications and limits the possibilities for broader development. Strategies grouping SMEs into collaborative networks are possible but sometimes need a strong leader to ensure credibility. On the other hand, large integrator-operators cannot be proficient in all the necessary domains, particularly when applications move very fast. They very much need the diversity and the dynamics of these SMEs to provide service packages with a common service backbone. Uniting the different actors is a challenge displaying good promises from various perspectives including sustainability. However, it is necessary that the links between the different partners and their corresponding activities be correctly represented in a model to be understood. This article proposes a new model for activities and processes in firms collaborating together in a network. A clearer understanding of the organisation acquired with the model, which is then used to discuss sustainability issues within the network.