Smartphones have become integral to daily life, impacting various aspects from banking to social networking. The global smartphone market is experiencing significant growth, projected to reach $792.51 billion by 2029. This growth is intertwined with the advancement of telecom services in speed, accuracy, and bandwidth, enabling features like high-resolution video streaming and virtual reality. Understanding consumer loyalty within this smartphone-telecom service ecosystem is crucial. This study focuses on the interplay between device and carrier choices, recognizing that user experiences are shaped by the synergy between device performance and network quality. In technologically advanced markets, like South Korea, this compatibility significantly impacts user satisfaction and loyalty. While smartphone purchases are often driven by brand image (e.g., Samsung Galaxy vs. Apple iPhone), mobile carrier selection leans more towards corporate image, reflecting perceptions of service quality and reputation. The cost of smartphones and subscription fees also play a significant role in consumer satisfaction. The abundance of smartphone apps and their seamless functioning are also key determinants of user experience. This study addresses a critical research gap by exploring the integrated loyalty between smartphones and mobile carriers, unlike previous research that treated them separately. The study aims to unravel the mechanisms influencing satisfaction with both devices and carriers, identifying factors driving overall loyalty.

The literature review examines existing research on smartphone usage and telecom services. Regarding smartphones, studies have applied the Technology Acceptance Model (TAM), highlighting perceived usefulness and ease of use as critical drivers of adoption. Research has also incorporated emotional responses within mobile apps, extending TAM and exploring the role of brand image, product features, and price in shaping purchase intentions. The Expectation-Confirmation Model (ECM) has been used to study user satisfaction and continuance intention, emphasizing the mediating role of satisfaction between expectation confirmation and brand loyalty. In the context of telecom services, research has focused on service excellence, customer satisfaction, and loyalty, examining the impact of service quality, trust, and commitment. Studies also explore brand switching behavior, identifying factors like technology, pricing, switching costs, and service failures. The literature review highlights a gap in understanding the integrated loyalty to both smartphones and telecom companies.

This study employed a quantitative research design using an online survey distributed to smartphone users in South Korea between February 5th and September 23rd, 2022. Convenience sampling was used, with the survey link distributed through partnerships with cellular retail outlets. 357 complete responses were analyzed after filtering out incomplete data. The sample comprised 55.5% males and 44.5% females, with the majority (71.1%) using Samsung phones and most subscribed to SKT (57.1%). The sample size was determined using an a-priori sample size calculator for SEMs to ensure adequate power for the analysis. The study used a validated questionnaire, translated into Korean and back-translated into English, incorporating items based on validated scales from previous research. All variables (except demographics and frequency) were measured using a 7-point Likert scale. Partial Least Squares Structural Equation Modeling (PLS-SEM) using SmartPLS 4.0 was employed to analyze the data, suitable for handling both formative and reflective assessments. Common Method Bias (CMB) was assessed using principal component analysis. The measurement model was evaluated for reliability (Cronbach's alpha, composite reliability), convergent validity (factor loadings, average variance extracted), and discriminant validity (Fornell-Larcker criterion, HTMT ratio). The structural model was assessed using indices such as SRMR, D_ULS, d_G, and bootstrapping was used to test hypotheses.

The PLS-SEM analysis revealed several key findings: 1. **Brand image significantly and positively influenced device satisfaction (H1 supported).** This supports previous research on the importance of brand perception in consumer satisfaction. 2. **Price fairness did not significantly impact device satisfaction (H2 not supported).** This suggests that the perceived value of smartphones may outweigh price concerns. 3. **Applications significantly and positively affected device satisfaction (H3 supported).** This highlights the importance of app functionality in overall device experience. 4. **Applications had a positive but not significant effect on mobile carrier satisfaction (H3b not supported).** The relationship between apps and carrier satisfaction may be less direct than that between apps and device satisfaction. 5. **Call quality did not significantly affect device or carrier satisfaction (H4a and H4b not supported).** This suggests high call quality is the norm, reducing its influence on satisfaction. 6. **Corporate image significantly and positively influenced mobile carrier satisfaction (H5 supported).** Positive brand perception significantly contributed to carrier satisfaction. 7. **Perceived fee did not significantly influence mobile carrier satisfaction (H6 not supported).** This suggests other factors may dominate fee concerns. 8. **Device satisfaction significantly and positively influenced loyalty (H7 supported).** User satisfaction is a key driver of loyalty. 9. **Mobile carrier satisfaction significantly and positively influenced loyalty (H8 supported).** Carrier satisfaction also contributes significantly to overall loyalty. The structural model explained approximately 68.8% of the variance in loyalty, indicating a relatively robust model.

The findings highlight the multifaceted nature of loyalty within the smartphone-telecom service ecosystem. While brand image strongly influences device satisfaction, price fairness played a less significant role, possibly due to consumers' willingness to pay for enhanced functionality and value. The significant positive influence of apps on both device and carrier satisfaction underscores the importance of a well-functioning app ecosystem. The lack of impact of call quality on satisfaction may reflect the high quality standards in the market. Corporate image's strong influence on carrier satisfaction emphasizes the role of reputation and service quality. The study's confirmation that both device and carrier satisfaction contribute to loyalty provides valuable insights for enhancing customer retention. The results suggest a stronger influence of device satisfaction on loyalty, emphasizing the significance of focusing on enhancing device-related aspects, particularly brand image and app functionality.

This study makes several important theoretical and practical contributions. Theoretically, it advances our understanding of integrated loyalty by considering the intertwined relationship between smartphones and mobile carriers, extending existing models of loyalty. Practically, it provides actionable insights for smartphone manufacturers and mobile carriers to enhance customer retention by focusing on brand image, app functionality, and corporate image. Future research could explore the role of other factors (e.g., customer service, network speed) in influencing satisfaction and loyalty, and conduct a longitudinal study to assess the stability of loyalty over time.

The study used convenience sampling which limits the generalizability of the findings. The cross-sectional design restricts the ability to infer causality. The study focused on South Korean users, so findings may not be directly generalizable to other cultural contexts. The definition of loyalty used in this study primarily focused on comparative satisfaction and referral willingness, neglecting other aspects such as price insensitivity and future behavioural intentions. Finally, the study did not distinguish between true loyalty and the effects of customer lock-in (switching costs).