Recommendation ITU-T P.382 specifies critical physical and electroacoustical characteristics for a universal headset interface with more than four terminals and provides corresponding test methods. Headset or headphone (HP) interfaces of diameter 3.5 mm and 2.5 mm have been widely used in digital mobile terminals during recent years. Nowadays, the consumer is free to choose either the headset or HP originally provided by the terminal manufacturer or others that are offered separately. However, the quality of service/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 connected headset or HP.