The trunk prefix for dialing long-distance calls, across numbering plan area (NPA) boundaries within Canada or to other NANP countries, is also 1.
Overseas calls to locations outside the NANP are dialled with the 011 international prefix, followed by the country code and the national significant number.
The effort eventually led to Direct Distance Dialing (DDD) by telephone subscribers, and the North American Numbering Plan.
Yukon, and the far northern regions, nor Newfoundland and Labrador, which was a British dominion at the time, were not included in the first assignments of 1947 for lack of telephone service.
Locations with service bordering a numbering plan area, were later served with codes of the regional carriers, such as Northwestel, with toll-routing infrastructure.