Furuno FM-8800D Service Manual page 17

3) Press [ENT] key. Then "Received Message" window is changed to "Send Message".
Press and hold down [CALL] key more than 3 seconds to transmit TEST ACK
message.
After the transmission, the "CH16" window is displayed.
4) Open "RCVD ORDINARY" LOG window and check a LOG of "TEST CALL".
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