The continent of North America has unique three digit area codes for each of its member countries. The territories of these countries stand diverse from each other with the help of these unique area codes that make it possible to classify the North American countries into Numbering Plan Areas (NPA). This entire system of the continent’s area classification is what’s known as North American Numbering Plan (NANP).
There are certain rules to be honored when it comes to designing Numbering Plan Areas (NPA).
The existing assigned codes are 800, 888, 877, 866, 855, 844, and 833. A set of area codes are soon to be released in the future, which are 822, 880, 887, and then followed by 889. About Phone Number Allocation in North America
There are area codes within the US, as well as outside the US. On a whole there are a total of 395 area codes in the world with 317 in the US, 41 in Canada, 17 non-geographic, and 20 others that are mostly located in the Caribbean. In US, California has the highest number of area codes standing at 32, followed by Texas with 26, New York with 18, Florida with 17, and Illinois with 13.
The allocation and numbering plan of the US and its territories, Canada and the Caribbean is controlled by the North American Numbering Plan Administration (NANPA). Therefore the NANPA organizes all the allocation and numbering of the area codes and telephone prefixes to various phone companies. The typical format of a phone number in any of these countries is NPA-NXX-XXXX or (NPA) NXX-XXXX.
Breaking down the format further,
NPA- NPA codes were originally developed by AT&T and the Bell System, to divide the coverage areas into "number plan areas" also known as “area codes”. These area codes came into existence during the early 1940s. While the system was developed in the 40s, direct long distance dialing did not begin until the early 50s. Also, not all area codes are currently put into use. Of all, a few area codes are reserved for special purposes. For instance, area code 800 (usually referred to as 800-numbers) is reserved for toll free calls where the receiving party is charged instead of the calling party.
NXX- The following three digits of a landline or cellphone number are called as the NXX. The NXX is also known as the prefix or exchange. Various telephone carriers reserve blocks of telephone numbers by reserving an NXX within an area code. Like area codes, not all prefixes are currently in use.
Subscriber- At last, the final 4 digits of the phone number are known as subscriber or local number. Based on the total number of active NPA and NXX combinations reserved and that each one could have up to 10,000 possible subscriber numbers, the current total possible number of telephone numbers is 1,699,140,000. Based on the total population of the US and Canada according to the US Census and the World Bank, it leaves up to 4 phone numbers for every person. Keep in mind that phone numbers in this era are not only traditionally used for landlines but also for fax machines, cell phones or wireless phones, or internet connections, making it necessary for one individual to have multiple phone numbers.