The North American Numbering Plan or NANP is the Governing Body for North American countries that share its numbering resources. These countries include the United States, Canada, Bermuda, Anguilla, Antigua & Barbuda, the Bahamas, Barbados, the British Virgin Islands, and the list goes on… When I started working with Voice I began looking at phone numbers much the same way I look at IP addresses. Just like the NANP there is also a Governing Body in place for IP and Domain names ICANN. Phone numbers are routed much like IP address and there are techniques in place to preserve numbers based on their regions or area code.
North American Numbering Web Site – http://www.nanpa.com
NPA
The NPA or Area Code is the 3 digit identifies often refereed to as the Local Area Code.
- The Numbering Plan Area
- The first digit can range from [ 2 – 9 ] the remaining digits range from [ 0 – 9 ]
NXX
Central office codes, also known as exchanges, prefixes, or simply NXXs, digits assigned to geographic regions. The NANPA assigns central office codes to state authorized local service providers using industry developed guidelines and federal directives. Because the application and qualification process is complex, potential applicants should read and understand the guidelines.
- The N digit can range = [ 2 – 9 ]
- The X digit can range = [ 0 – 9 ]
XXXX
The Subscriber number or Station code is the 4 digit number assigned to the Customer.
- The X Digit Range [ 0 – 9 ]
Examples – NPA NXX-XXXX
- Good: 816 235-1234
- Bad: 816 911-1234 – The NXX cannot be in the form N11
- Good: 913 234-1234
- Bad: 123 234-1234 – The NPA cannot begin with 0 or 1
Dialed Number Identification Service
The Dialed Number Identification Service or DNIS is a service offered by Telecommunications companies that allows a corporate company to determine which telephone number was dialed by a customer. This is a powerful tool when a Corporation has numbers of PRI’s with Direct In-word Dial or DID numbers for Employee’s or Call Centers. The Telecommunication company sends the DNIS number to the Corporate client phone system or PBX via the PRI during the call setup processes. The DNIS number is typically a 4 to 10 digit number. The Corporate customer can request the length or number of digits based on their individual needs.
Automatic Number Identification
The Automatic Number Identification or ANI is the process or feature offered by Telecommunication companies for the main purpose of billing. Basically this feature keeps track of placed calls or received calls from the calling number or numbers. The setup or process of providing this information is determined by the Telecommunication provider by sending the digital tone multi frequency or DTMF tones along with the call. It’s also possible for a residential Customer to use the ANI to screen callers.
I hope you found this post on North American Number Plan helpful and informative. Be sure to let me know what you think by leaving suggestions, and feedback in the comments section below. You can find out more about these and other articles be checking out recent posts and archives. To learn more about me be sure to check out the About page. And as always thanks again for visiting The Packet.
