The rapid growth of mobile device usage stimulates the application of high-speed mobile broadband services. Thus, the adoption of Long Term Evolution (LTE), the leading standard of the fourth generation (4G) of mobile phone communication technology, becomes the main growth strategy for carriers. However, the LTE network services do not transmit voice data until the Voice over LTE (VoLTE) initiatives. This study applies quality function deployment (QFD) to explore the customer requirements and identify prospective technologies of VoLTE services. Our research shows that the top three important VoLTE techniques are related to “improve efficiency and resource utilization”, “enhance the functionality of the handover selection function nodes” and “circuit switched service over a long term evolution network”. Furthermore, the study finds that VoLTE outperforms Over-the-top (OTT) services in most of the customer requirements, which assures that VoLTE has its competitive advantage when compares to OTT services in the mobile voice call services.