ITU prefixes: Letter combinations available for use in Canada as the first two letters of a television or radio station's call sign are CF, CG, CH, CI, CJ, CK, CY, CZ, VA, VB, VC, VD, VE, VF, VG, VO, VX, VY, XJ, XK, XL, XM, XN and XO. Only CF, CH, CI, CJ and CK are currently in common use, although four radio stations in St. John's, Newfoundland and Labrador retained call letters beginning with VO when Newfoundland joined Canadian Confederation in 1949. Stations owned by the Canadian Broadcasting Corporation use CB through a special agreement with the government of Chile. Some codes beginning with VE and VF are also in use to identify radio repeater transmitters.
The history of telegraphy in Canada dates back to the Province of Canada. While the first telegraph company was the Toronto, Hamilton and Niagara Electro-Magnetic Telegraph Company, founded in 1846, it was the Montreal Telegraph Company, controlled by Hugh Allan and founded a year later, that dominated in Canada during the technology's early years.
Following the 1852 Telegraph Act, Canada's first permanent transatlantic telegraph link was a submarine cable built in 1866 between Ireland and Newfoundland.Telegrams were sent through networks built by Canadian Pacific and Canadian National.
In 1868 Montreal Telegraph began facing competition from the newly established Dominion Telegraph Company. 1880 saw the Great North Western Telegraph Company established to connect Ontario and Manitoba but within a year it was taken over by Western Union, leading briefly to that company's control of almost all telegraphy in Canada. In 1882, Canadian Pacific transmitted its first commercial telegram over telegraph lines they had erected alongside its tracks, breaking Western Union's monopoly. Great North Western Telegraph, facing bankruptcy, was taken over in 1915 by Canadian Northern.
As of 1951, approximately 7000 messages were sent daily from the United States to Canada. An agreement with Western Union required that U.S. company to route messages in a specified ratio of 3:1, with three telegraphic messages transmitted to Canadian National for every message transmitted to Canadian Pacific. The agreement was complicated by the fact that some Canadian destinations were served by only one of the two networks.