STUDY ON THE LITERATURE AND BUSINESS MODELS USED IN THE IMPLEMENTATION OF CRM – THE CUSTOMER-BASED MODEL - AS A STRATEGIC AND CONDITIONING APPROACH IN THE COMPETITIVE ADVANTAGE IN THE SMES:  AN EMPIRICAL STUDY OF THE IMPLEMENTATION OF CRM – THE CUSTOMER-BASED MODEL - IN TRAVEL AGENCIES Guijarro María García Directed by: Dr. D. Ignacio Gil Pechuán The interest in the chosen topic can be explained and justified by the profound social and economic development we are witnessing worldwide over the last few decades. The tourism sector has become an important source of economic prosperity in many countries and a source of development for many others and has a fundamental importance in business, hence the relevance of analyzing the management of the companies of which it consists.  Lately, the New Technologies of Information and Communication (NTIC) have led to an increase in competition and to new ways of distribution of services within tourism (phenomenon of "intermediation" and "disintermediation"). Therefore, companies whose business consists of the distribution of tourism services need to develop strategies in order to enable and/or permit them to sustain their business in present times. Thus, personal relation-based marketing has emerged as a useful tool to achieve this goal, and more specifically the management of relations with customers (Customer Service Management). Customer-service management is not a novel concept, for a long time now; organizations have tried to give preferential treatment to those customers who have been loyal, thus succeeding in increasing their satisfaction and therefore their future purchases. However, due to the sheer size organizations are reaching due to the globalization of international markets, we need new and updated tools for managing the client portfolio, differentiating customers depending on the services provided to them. Customer management should be a business strategy within a company, a positive attitude towards employees as well as customers, supported by certain processes and systems. The aim is to build long lasting relationships between the customer and the company by meeting the needs and preferences of both parties, and thus a way of adding value to the company and the customer.  The empirical research related to this topic and the tourism sector is based, on the one hand, on the great social-economic worldwide relevance of the sector and especially in Spain, and on the other hand, on its development as a potentially  predominant sector in the economy of the future.    Choosing travel agencies (in this paper) has a double justification: on one hand, Internet´s part of NTIC has led to an increase in competition, as it requires travel agencies to develop strategies according to a reality in which these agencies are subjected to. On the other hand, one of the main functions of travel agencies is to advise; this implies a high degree of interaction with customers. In order to extend this relationship over time, mutual trust and communication between the parties is crucial. Thus, short-term management in travel agencies, which is still needed, has to be complemented with long-term management in order to ensure an operational system to match the new situation.  Therefore, the empirical research will attempt to answer the questions formulated in the first chapter of this thesis: 1.- Can the coexistence of two forms of the same business (online and off-line) have an impact on the perceived value by the client? 2.- Can a customer-based management (backed up by personal relation-based marketing and the adaptation to new technologies (internet)) improve a customer’s perceived value? 3.- Can a travel agency with a customer-based management achieve greater customer fidelity? 4.- Can a higher perceived value have an influence in customer satisfaction and fidelity towards the travel agency? 5.-  Do change related costs contribute to greater customer fidelity towards the travel agency?