North American telephone area codes 281, 346, 713, 832 and 936 serve Houston, Texas, and its environs. Area code 713, was one of the original area codes established with the North American Numbering Plan in October 1947. It originally covered the entire southeastern quadrant of Texas, from the Sabine River to the Brazos Valley. On March 19, 1983, the area was divided for the first time. The immediate Houston area retained area code 713 while the northern, eastern and western portions of the old 713 territory became area code 409.