Australia -South Australia/Northern Territory.
The Overland Telegraph Line - earliest recorded usage.

The earliest recorded form sent through the Overland Telegraph Line is shown below.

Eastern Feb 73

The message was sent from Sidney (sic - Sydney) to Bordeaux via Malta and Marseilles. It is an order for various alcohols to be sent to Noumea and it was received on 11 February 1873 - just less than 4 months after the submarine cable had been repaired by Eastern on 21 October 1872 and direct communications between Adelaide and England had commenced.

An extraordinary item - earlier by just over 6 months than the second earliest recorded date of 23 August 1873 - and again used by Curçier and Abet to order more drinks :)