This attribute indicates the encoding currently being performed on
this channel. g711 indicates that pulse code modulation (PCM)
defined by ITU-T G.711 is being performed. g726 indicates that
adaptive differential pulse code modulation (ADPCM) defined by
ITU-T G.726 is being performed. g728 indicates that the Low Delay
Coded Excited Linear Predictive Coder (LD-CELP) algorithm
defined by ITU-T G.728 is being performed. g729 indicates that the
Conjunctive Structure Algebraic Code Excited Linear Predictive
Coder (CS-ACELP) algorithm defined by ITU-T G.729 is being
performed. v27 indicates that the algorithm defined by ITU-T V.27
is being performed. v29 indicates that the algorithm defined by
ITU-T V.29 is being performed.