Prontonet User’s Manual v410 96
The left audio I/O channel is always assigned to Line 1 and the
right audio I/O channel is always assigned to Line 2.
3. Communications in Dual mode, Joint Stereo or Stereo at 64
Kbps: When we configure Encoder 1 to Dual mode, Joint Stereo or
Stereo at 64 Kbps, Encoder 2 is disabled since there are no free audio
inputs or outputs to assign to it.