Outsourcing in manufacturing as well as in services has granted enterprises strategic advantages such as lower cost yielded by economies of scale (at the vendor), greater technical competence, fast acquisition of new competencies, less investment needs, and sharper focus on products and markets, among others. This scenario promotes the collaborative relationship whereby enterprises change their emphasis from the immediate gain in individual transactions to strategies that seek repetitive transactions with preferential partners for enhancing efficiency and effectiveness in the long run. By means of a case study this research aims to verify, in the relationships of an enterprise and some of its important suppliers, to what degree the efficiency of operations is associated to the key elements of collaboration found in the literature. The research has been conducted in a telephone company along a three-month period when a structured questionnaire was filled out by the managerial and supervisory personnel. The data from the survey were confronted with the performance indicators regularly collected by the company for measuring and monitoring the outsourced services. The results suggest that there is, indeed, a positive correlation between the levels of the more important factors related to the collaborative practices and the good performance of the partnership.