Bush Telegraph Meaning

Example : 2007, "From Sudan to supermodel stardom," msnbc.com, 28 Aug. (retrieved 19 Sep. 2008):  When I was born, family and friends came from all over, thanks to the bush telegraph. There were very few telephones where I grew up, so my father mentioned my birth to someone at the market. And that woman told a man who was delivering rice to a place up the road. He told someone there, who was taking a herd of cattle south, toward the villages. And pretty soon the news of my birth had spread far and wide.1911, Jack London, Adventure, ch. 9:  I suppose you've received information, by bush-telegraph, that that third assistant understrapper and ex-sailorman at Tulagi is going to deport me as an undesirable immigrant.