North American Numbering Plan is the board of directors that assigns area codes to Canada, the US, and various US territories. The original concept was to have the country code (+1), area code, exchange, and then subscriber number. With this set up, all domestic NANP numbers are 10 numbers long even though I feel they should go to the maximum 12 digits as set by the ITU?. However, there are a couple of things to consider. No telephone number can have 0 or 1 as the first or fourth digits. Also since almost every telephone service provider provides domestic calling throughout the NANP, there is little concern with the area code nowadays. Someone with the 412 area code (Allegheny County Pennsylvania) can live in the most western point of Alaska, and still have the 412 number. This is because of local number portability. This allows a customer to keep their phone number, and move it to a telephone service provider of. their choice.
When both companies involved are cellular providers, a number can transfer to the new carrier usually within less than a day. However, anytime a terrestrial service provider is involved, it could take a week or two for the transfer to take effect. The old provider must remain active until the transfer is finalized. Once this happens, it will terminate the respective account, and you shouldn’t be charged by your former provider again unless you are post-paid.