ITU-T Recommendation P.313 provides audio performance requirements for portable digital cordless and mobile handsets, headset and speakerphone sets. The requirements apply to narrowband systems (3.1 kHz) regardless of the coding algorithm used in the terminal. Associated test methods are also given. Requirements are specified for the major electro-acoustic performance parameters affecting audio quality, including sending and receiving levels, frequency responses, noise, sidetone, stability, echo path and delay. The requirements given in this Recommendation should ensure satisfactory service quality in a high percentage of installations under normal conditions. Major changes over the previous version of this Recommendation (2007) are as follows: -Specifications for wideband handset, wideband headset and wideband hands-free terminals have been added. -The use of Type 1 and Type 3.2 artificial ears are removed from this Recommendation. -For handset terminals the test of Speech Quality in presence of ambient noise have been added. -For most of the test point is no longer ERP for receive but the diffuse-field. -Requirements for some test such as frequency response, distortion and linearity have been updated.