1876 The shore end of the Backstairs Passage was laid successfully on Christmas Day, at Kingscote, Kangaroo Island. The telegraph steamer Edinburgh returned to Normanville this afternoon. Seven miles of the Backstairs Passage cable have been laid. The cable starts from half a mile north of Yankalilla jetty, and goes out at right angles for three miles; then curves to Nepean Bay to join the line thirty miles to Cape Borda.LATER INTERCOLONIAL NEWS. (1876, January 4). The Mercury (Hobart, Tas. : 1860 - 1954), p. 3. http://nla.gov.au/nla.news-article8942149 Image from https://blog.kaspersky.com/telegraph-grandpa-of-internet/9034/
The Kangaroo Island telegraph, between Kingscote and Cape Borda, was completed on July 7. All that remains to be done to finish the contract is the burning of a few miles of scrub along the line. The contractors experi-enced some difficulty and delay in the prose-cution of their work, in consequence of the boggy nature of the ground. On the erection of the instruments on the island, communication will be established with Adelaide.Express and Telegraph (Adelaide, SA : 1867 - 1922), Monday 17 July 1876, page 2
1908 : The cable has been out of order for some time :http://nla.gov.au/nla.news-article56876784
The cable between Kangaroo Island and the mainland, which was repaired a few months ago, is to be permanently joined up next Wednesday when it will be lifted and a fresh splice made. The cable has given a great deal of trouble during the past few weeks, causing considerable delay to business.Kangaroo Island Courier (Kingscote, SA : 1907 - 1951), Saturday 29 February 1908, page 4
NEW TELEGRAPH STATION, KANGAROO ISLAND.—The telegraph line from Kingscote to Cape Willoughby, Kangaroo Island, has been completed, and there is now through communication between Cape Willoughby and Adelaide. This will enable the names of all vessels passing through Backstair's Passage to be telegraphed to the various telegraph stations in the colony, thus making a very desirable addition to the general shipping news available for the public. The line was constructed by Mr. Walter Thompson, contractor, who has been but a few months over the work. Its cost, roughly estimated, has been about £2,500, its total length being about 45 miles. Leaving Kingscote the wires are affixed to the same poles as those of the Cape Borda line for about six miles, at which point the two lines branch away in opposite directions. The telegraph-poles are of iron throughout.
Island Cable Interrupted,
1916 Since the 4th inst., Kangaroo Island has been without communication with the mainland, beyond the bi-weekly mail service, owing to a break in the cable between Yankililla [sic] and Kingscote, and much inconvenience and annoyance is caused business people in consequence. We note by the city dailies that the s.s. Ferret has been charted by the Post and Telegraph Department for the purpose of picking up and repairing the cable. This vessel called at Kingscote on Wednesday and after testing sailed for Yankililla, near which place it is thought the break occurs. Not only have Island residents been inconvenienced by this fault, but no shipping news has been received at Port Adelaide for over a week. This is the second or third occasion that communication has been held up within our knowledge and it might be timely to suggest that this cable, laid down about forty years ago be done away with and a wireless station established on the Island.Kangaroo Island Courier (Kingscote, SA : 1907 - 1951), Saturday 12 August 1916, page 2