The talk button learns the network road the voice keyer already took: when
To-radio is the radio itself, the microphone is captured and re-framed into
the rig's 320-sample packets, the capture callback serving as the clock — the
mic delivers in real time, so no ring and no pacer. Counters and the frame
remainder live on the audio stream, so a talk session spans calls. PTT keys
before and releases after, through the same code as the USB path.
With this, a network Icom is a complete remote station over three UDP ports:
RX audio to the headset, live voice and recorded messages back, CW through
the rig's keyer, CAT for everything else.