This research investigates the influence of service quality on purchase decision in the mobile phone retail market, as well as a relationship between the consumer’s previous knowledge of mobile services and the importance of salesmen help during the sales encounter. In order to achieve that, a survey was conducted in Rio de Janeiro city using mobile phone retail stores as its research locus. Among other factors, the survey measured consumer’s previous knowledge of mobile services, consumer satisfaction, the importance attributed to salesperson’s help during the sales encounter and the intent to purchase. The quantitative phase was preceded by a qualitative one, in order to acknowledge which were the consumer’s most used attributes to measure service quality. As a result, it was found, in agreement with other previous studies, that service quality positively impacted on purchase decision. The results and both the academic and managerial implications are discussed in this work. Finally, suggestions of future studies are provided alongside the analysis.