Furuno FM-4800 Operator's Manual page 41

Initiate a position request call to a vessel registered in the
directory
Before you initiate a position request call from the individual directory, a vessel or
person's name and the MMSI number associated with the vessel you want to
transmit the call should be added to the individual directory. For information about
how to add entries to individual directory, see section 11.1.1 Adding an Entry.
On the "POS REQUEST" interface, press the Menu/DSC control to select
Step 1
"DIRECTORY".
Select an individual contact, and then press the Menu/DSC control.
Step 2

When CH70 is busy, the following screen appears. You can wait
without pressing any key until CH70 is idle.

When the CH70 is idle, the following screens appear, and the radio
waits for an acknowledgement.
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