As part of the training Master 2 in Business Administration, Operations Research work is carried out.The research is presented as a memory validated and defended in front of a panel of professors.It is in this perspective that we reflect on the topic "Customer Relationship Management as a Tool of Satisfaction of Customer and Company: The case of SONATEL Dakar."　　This topic is very interest because telecom sector is spearheading Senegal.In recent years, mobile telephony, internet, fixed merge simultaneously growth dynamism and innovation due to increased competition in this market segment.　　Customer Relationship Management (CRM) is a branch of marketing.It is more relevant in the field of telecommunications as it is essential for any business.CRM allows the company to build a single customer relationship as the company and the customer gain from the exchange, providing both parties benefit in the long term relationship.　　The purpose of this research is to analyze the CRM and also evaluate customer satisfaction of SONATEL Dakar.To approach this understanding, the thesis begins with three questions on which the first studies were published.Among these previous studies were collected and through them a questionnaire was created and submitted to 102 persons, taken as sample, within the customers of SONATEL Dakar.Then the data were collected and were analyzed by using SPSS software.　　The findings show that there has a relationship between a successful CRM and customer satisfaction and company.The study shows that CRM is a pillar of customer satisfaction.Indeed, if a customer is satisfied it is faithful and profitable for the company.It was also found that the relationship between SONATEL and his client should be improved.Most customers are satisfied because of the quality and safety of the products as the relationship with the company.　　The recommendations, in summary, are that the company should more invest in the relationship with their clients and also reduce the tariffs.SONATEL should insert a policy to train and teach the CRM tools to these agents and especially who are in direct contact with customers.Customer loyalty depends on his degree of satisfaction.