ITU-T P.342 PDF

This Recommendation provides audio performance requirements for hands-free and loudspeaking telephones using, in the telephone narrow-band (300-3400 Hz), the waveform encoding according to [ITU-T G.711] (PCM at both 64 kbit/s and 56 kbit/s) and [ITU-T G.726] (ADPCM 32 kbit/s).

Audio performance requirements for headset terminals are included in [ITU-T P.310]. IP terminals are not included in this Recommendation. Audio performance requirements for digital telephones using coding schemes other than waveform encoding and at bit rates lower than 32 kbit/s are under study.