Recommendation ITU T P.381 specifies critical physical and electrical-acoustical characteristics for the universal headset interface and provides corresponding test methods. Both 3.5 mm and 2.5 mm diameter headset/headphone interfaces have been widely used in digital mobile terminals in recent years. Nowadays, the consumer is free to choose either the headset/headphone originally provided by the terminal manufacturer or others that are offered separately. However, the quality of service (QoS)/quality of experience (QoE) perceived by users is influenced by both the electrical performance of the interface and the compatibility between the terminal and the connected headset/headphone.

TSB Note: For the purpose of the approval process, the electronic attachment can be found at https://www.itu.int/ifa/t/2017/sg12/exchange/wp1/q3/p381/P381_AnnexA_PrerecordedSignals.zip The MD5 checksum of the file is 0c30568cc690cca2b3544e147a9a5aaa