This is the National Destination Code(NDC):204 page list. Its detail is as below.
Area code 204 is one of the original 86 area codes created by AT&T and the Bell System in 1947. It originally served the entire state of Manitoba. In 2012, area code 431 was created as an overlay to area code 204. To avoid exhausting all possible phone numbers in this area code, relief planning has begun. Currently, it covers the entire state of Manitoba, and it overlaps coverage areas with area code 431.