Area code 604 is one of the original 86 area codes assigned in 1947 in the contiguous United States and Canada. It designated the province of British Columbia. 604 also served Point Roberts, Washington, a pene-enclave of the United States until 1968, when the area was reassigned to area code 206; since 1995, it is served by area code 360.
Despite British Columbia's growth in the second half of the 20th century, 604 remained the province's sole area code for nearly 50 years. By the mid-1990s, however, the need for a new area code in the province arose from rapid expansion of telecommunication services for cell phones and pagers. The number shortage was particularly severe in the Lower Mainland, which was home to most of the province's landlines and most of its other telecommunications devices requiring telephone numbers.
On October 19, 1996, numbering plan area 604 was reduced to span Vancouver and the Lower Mainland, including the Sunshine Coast and Whistler, with the remainder of the province served by the new area code 250.[1]
Although the 1996 split was intended as a long-term solution, within three years, 604 was close to exhaustion once again, due to the continued proliferation of cell phones and pagers. Numbers tended to be used up fairly quickly in Vancouver and its immediate neighbours.
On November 3, 2001, area code 778 was implemented as a concentrated overlay for the two largest regional districts in the Lower Mainland, Metro Vancouver and the Fraser Valley Regional District. The experiment was announced in NANPA Planning Letter 246.[2] The remainder of the Lower Mainland continued to use only 604, but the addition of area code 778 required the implementation of ten-digit dialling throughout the region.
The Canadian Radio-television and Telecommunications Commission (CRTC) announced on June 7, 2007, that 778 would become an overlay for the entire province on July 4, 2007.[3] Effective June 23, 2008, ten-digit dialling became mandatory throughout the entire province of British Columbia, and attempts to make a seven-digit call triggered an intercept message with a reminder of the new rule. After September 12, 2008, seven-digit dialling was no longer functional.[4] Overlays have become the preferred method of relief in Canada, as they offer an easy workaround for the number allocation problem.
On June 1, 2013, area code 236 was implemented as a distributed overlay of area codes 604, 250, and 778 and was expected to be exhausted in May 2020.[6][7] As a result, area code 672 was implemented as an additional distributed overlay on May 4, 2019, to relieve area codes 604, 250, 778, and 236.[7]
