Area code 604 is one of the original 86 area codes assigned in 1947 in the contiguous United States and the nine numbering plan areas (NPAs) of Canada. It designated the province of British Columbia. Until 1988, 604 also included Point Roberts, Washington, a pene-enclave of the United States; Point Roberts was transferred in 1988 to area code 206 and is now 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 could no longer be staved off, largely because of Canada's number allocation system. Every competitive local exchange carrier in the country is allocated blocks of 10,000 numbers, corresponding to a single three-digit prefix, for every rate centre in which it offers service, even for the smallest hamlets.
While smaller rate centres usually do not need that many numbers, once a number is assigned to a carrier and rate centre, it cannot be moved elsewhere, even to a larger rate centre. Additionally, some larger cities are split between multiple rate centres that have never been amalgamated. That resulted in thousands of wasted numbers, and the growing popularity of cell phones, pagers and fax machines has only exacerbated that problem. 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 phone numbers.
In 1997, 604 was cut back to the Lower Mainland, with the new area code 250 created for the remainder of the province.[1]
The 1997 split was intended as a long-term solution for the Lower Mainland. However, within three years, 604 was close to exhaustion, once again because of the aforementioned number allocation problem and the continued proliferation of cell phones and pagers. Numbers tended to be used up fairly quickly in Vancouver and its immediate neighbours because of their rapid growth, but the number allocation problem was still severe in the Lower Mainland as a whole.
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 after the same number allocation problem that had afflicted 604 was bringing 250 close to exhaustion.[2] Effective June 23, 2008, ten-digit dialling became mandatory in 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.[3] Overlays have become the preferred method of relief in Canada, as they offer an easy workaround for the number allocation problem.
The incumbent local exchange carrier in 604 and 778 is Telus. Through "number portability" and sub-allocation of all numbers in some exchanges to a competitor, many numbers in the 778 area code are now serviced by Shaw Cablesystems.[4]
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.[5][6] 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.[6]
