Furuno LH-5000 Operator's Manual page 32

After completing your conversation, press the ALL key to return to
the home screen, or press the same selected key (IC1-IC6) to back to
previous mode.
Press the selected key (IC1–IC6) and hold the PTT key on the
microphone to answer the call.
Only in ALL mode, you can perform this function.
Release the PTT key on the microphone to receive.
After completing your conversation, press the ALL key to return to
the home screen, or press the same selected key (IC1-IC6) to back to
previous mode.
Press AFT, FWD, or BOTH key to select the horn speaker(s).
For example, if you press the FWD key, this key lights red and the
following information appears on the screen.
Press and hold the PTT key on the microphone and speak into the
microphone.