It looks like it's not
available in the dialplan, but at the C library level it seems
to be doable:
it will be great if a call could be split into two b-legs, one
for input audio, and the other one for output.
There are a number of usage scenarios when an operator needs to
listen and to speak to two different groups of people. This can
be partially achieved with a set of conferences bridged together
with mute option, but something more straightforward would be
great.
Another interesting scenario is when the operator speaks two-way
with someone, and is also able to listen to some other channel
at the same time.
regards,
stanislav