In the current economic climate and intense competitive environment achieving sustainable competitive advantage has become vital for any organisation’s survival. Organisations around the globe are seeking ways to distinguish themselves from their competitors and win customers. This paper attempts to study the significance of sustainable competitive advantage from the information service firms’ perspective. The paper argues that service firms can distinguish themselves and attain competitive advantage by performing well on operational performance elements that lead to customer satisfaction, loyalty and ultimately to profitability. Particularly, the paper empirically investigates the importance of dependability and quality in driving customer satisfaction and customer loyalty. The analysis shows that dependability is a key driver of customer satisfaction and customer loyalty. Thus, information service firms should focus more on improving the reliability of their services to achieve competitive advantage and later that may lead to a sustainable competitive advantage.