Are you sure you don't have equipment already present that cab be
coerced into providing an "activity" signal that could be used to
trigger a relay?  For instance, if there were a cisco router there
connecting the remote ethernet to the real world, it might be one
of the ones with an auxiliary serial port, capable of receiving
reverse-telnet connections and being connected to all manner of
equipment.  Ditto if the printer is connected to some sort of PC
or print server already...

BillW
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