Headsets and headphones equipped with wired or wireless digital interfaces have been widely used in digital mobile terminals during recent years. The consumer is free to choose either the headset or the headphone originally provided with the terminal or other headsets or headphones that are offered separately. However, the quality of service and quality of experience (QoS/QoE) perceived by users is influenced by both the electrical performance of the interface and the compatibility between the terminal and the headset or headphone. Recommendation ITU-T P.383 specifies requirements and provides corresponding test methods for headsets and headphones as well as terminals, when tested separately.