The NANP is the plan for telephone numbers in Canada, the US and its territories, and the Caribbean. Telephone number addresses in the NANP are in the form NXX-NXX-XXXX, where N is any digit from 2-9 and X is any digit from 0-9. (The format often is expressed as NPA-NXX-XXXX to reflect the fact that the first three digits of the telephone number represent the area code.) The first six digits (NPA-NXX) of the telephone number identify the local serving switch. The NPA-NXX of a telephone number also indicates the geographic area (“rate area”) associated with the number. There are exceptions to the meaning of a number’s NPA-NXX, such as for “toll-free” numbers and those in certain specially designated NPA-NXXs.