Customer-oriented processes are essential to achieve customer satisfaction. This research describes the application of the concepts of Relationship Marketing as a starting point in the process of developing new services in a telecommunications service provider in Spain. In the quest to increase customer satisfaction, this paper seeks to understand whether the structure of internal processes is the most suitable to channel customer requirements using relationship marketing philosophy but in order to use a systematics tool and a robust method; DMAIC methodology of Six Sigma is applied. Previous researches have contemplated the used of Six Sigma methodologies within manufacturing industries, while this research tries to explore a unique niche by shifting from a production approach, to a service-process, where few researches are found. The scientific research is initiated with the exploration of New Service Development (NSD) processes in the company allowing the preparation of As-Is process maps. Two ways or scenarios are identified for developing new services in the company; the first one where “Standard Services” are developed and proposed by the company, while in the second scenario, services born from a specific customer requirement and known as “Special Projects”. The collection of the Voice of the customer (VOC) identifies 13 criteria that are essential for purchasing, making possible to compare the linkage between internal activities with customer requirements. In a final stage the methodology proposed is validated with a service within the company portfolio. Significant contributions of this research are presented through the framework proposed so as to measure the performance gaps within the services provided by company, regardless of their lifecycle stage, which can also be extrapolated to other businesses of the group. Moreover it provides an understanding on the impact of each process activities in a specific requirement highlighting the most Critical to Quality (CTQ) activities and proposing improvement opportunities.