<p>Hamrah Aval, the first and largest mobile network operator in Iran, operates in a highly competitive telecommunications industry, where customer retention and satisfaction are crucial for sustaining market leadership. In this context, relationship marketing is recognized as a strategic approach for fostering trust, commitment, and long-term engagement, thereby enhancing customer loyalty and satisfaction. This study investigates the extent to which relationship marketing tactics influence these outcomes at Hamrah Aval. A descriptive-correlational design was employed, using structural equation modeling (SEM) with path analysis. The statistical population comprised approximately 1100 employees and managers in operational districts 2 and 3 of Tehran, with managers included within the broader employee sampling frame. These districts were purposively selected due to their strategic importance in terms of customer volume and service coverage, making them representative of the company’s operational core. A stratified random sampling method was applied, and Cochran’s formula determined a final sample size of 310 participants. Findings reveal that relationship marketing tactics exert a strong, positive, and statistically significant influence on both customer loyalty (effect coefficient = 0.881) and satisfaction (effect coefficient = 0.888), suggesting that even incremental improvements in their implementation can yield substantial gains in customer engagement. Beyond confirming the central role of relationship marketing in service-driven industries, the results highlight its value as a source of sustainable competitive advantage. By strengthening loyalty and satisfaction, Hamrah Aval can secure its current customer base and enhance its positioning against rivals in a rapidly evolving and increasingly competitive telecommunications market.</p>