Australia's first telegraph line was built by a recently immigrated Canadian named Samuel McGowan. Sponsored by the Victorian government, the 17-kilometer line between Melbourne and Williamstown went into operation in March 1854, less than a decade after the world's first public telegraph line had opened between Baltimore and Washington, D.C. in 1844. Four thousand telegrams were dispatched in that first year. By December 1856, connections reached the gold-mining centers of Ballarat and Bendigo. In South Australia, the colonial government recruited Charles Todd from London to serve as superintendent of telegraphs. Todd arrived in Adelaide in November 1855, only to find that an architect named James Macgeorge had already beaten him to it, stringing a single wire from Adelaide to Semaphore by routing it away from the main road to dodge government restrictions. Macgeorge's line used Cooke and Wheatstone's equipment; Todd's was technically superior and more direct. By February 1857, Macgeorge's telegraph was redundant.

Both Todd and McGowan dreamed that their intercolonial lines would become links in a chain reaching to England via India. The Adelaide to Melbourne connection, completed in July 1858, was the first step. But the real prize was a connection to the outside world, and for sixteen years, competing colonies and foreign entrepreneurs jockeyed for position. Four routes to a submarine cable landing were serious contenders. Todd won. The Australian Overland Telegraph Line, running 3,200 kilometers from Adelaide through the desert interior to Darwin, was completed in 1872. A submarine cable from Java met the overland wire at Darwin, and on 19 November 1871, Australia received its first international telecommunications message. The cable failed soon after and was not fully restored until October 1872, but the connection held. A continent that had waited months for news from Europe could now receive it in hours.

In 1874, the South and Western Australian legislatures funded the East-West Telegraph Line from Port Augusta to Albany, allowing Western Australia to connect to the Overland Telegraph and its submarine cables to Indonesia and beyond. At the time, Western Australia had a population of 25,000 and total government revenue of 135,000 pounds per year. The estimated cost of the line was 30,000 pounds. Construction began from Albany through country known to be practically waterless, reaching Esperance in 1876, Eucla in 1877. The telegraph operated for fifty years before being replaced in 1927 by a more maintainable line alongside the transcontinental railway. Engineers Australia now lists the East-West Telegraph as a National Engineering Landmark. The Perth-to-Albany connection, completed in 1870, had its own strategic logic: steamer ships from England routinely stopped at Albany for supplies, and if their news and messages could be intercepted and wired to Perth, Western Australia gained a commercial edge over the eastern colonies.

The social impact was enormous. Marine archaeologist Dr. Silvano Jung called the telegraph "a national revolution that started in Darwin," reducing the crushing weight of Australia's geographic isolation from the rest of the world. Telegram usage climbed steadily, peaking at 35 million messages per year in 1945. After that, the telephone began to erode the telegraph's dominance, both because calls were cheaper and because the network kept improving. Teleprinters took over more and more traffic from 1954. In 1959, an automated switching system called TRESS allowed messages to be retransmitted to their final destination without a human operator. The last telegraph message sent exclusively by land line went in mid-1963. The last Morse code message on the eastern seaboard was tapped out in early 1963. The final publicly provided telegraphy service in Australia closed in 1993, more than 139 years after McGowan's wire between Melbourne and Williamstown first crackled to life with news of a rebellion.