Technical and financial factors and the deregulation of the telecommunication field are often used to explain both the use of the cellular phones and the satisfaction of end-users in developing countries. Little attention, however, has been paid to factors such as perceptions, motivations, and social variables which directly influence the decision of an individual to adopt and use a cellular phone. This study aims at better understanding the effect of these factors on the utilization of cellular phones. A questionnaire survey was conducted among cellular phones users in Guinea. Results obtained from a sample of 463 respondents show that familiarity, social influence, and the needs for mobility required by the task are key determinants of cellular phones’ use.