The sustainability of South African telecommunications companies is under threat. Such threats are as a result new regulations that allowed influx of new entrant in the form of ISPs (Internet Service Providers) and the emergent of over-the-top (OTT) applications in recent years. This research seeks to understand the factors that influence a sustained competitive advantage despite all the challenges in the telecommunications industry in South Africa. The research explained the relationship that exist between service quality and sustained competitive advantage as well as the relationship that exist between intellectual capital and sustained competitive advantage. The study looked at the influence from both an internal perspective and external perspective. The internal perspective analysed the three constructs that make up intellectual capital namely; human capital, structural capital and relational capital. The external perspective used the SERVQUAL model to analyse how customers perceive services they expect to get from the telco providers and how they perceive the services after an encounter with the telco provider. The SERVQUAL model looks at five constructs of service quality namely; tangibility, reliability, responsiveness, assurance and empathy. The results of the study show that in the telco industry, relational capital is the most important dimension of intellectual capital followed by human capital, with structural capital coming up last. On the service quality variable, the research shows that customers see assurance as the most important dimension of service quality. With this in mind, the telco companies need to focus on their relational capital and human capital which includes customers and suppliers. They also need to focus on the assurance and responsiveness part of service quality. These variables will then influence future behaviour of customers (external view) as well allow employees to forge relationships that are long lasting and develop skills continuously (internal view). These dimensions are critical for the telco providers to achieve a sustained competitive advantage.