Today we’re announcing a new service for our clients: If you sign up for our LERG Refresh service we’ll provide quarterly updates to your Metaswitch translations that include the latest information from the LERG (new NPA-NXXs in your rate centers and LATAs) so that you’re able to successfully route and bill all calls correctly. Please fill out our contact form if you’d like to know more.
In honor of this new service, I’ve been doing some research about the history of phone numbers – in particular the North American Numbering Plan (or NANP) – and it’s actually pretty interesting.
Origins of the NANP
Before the NANP, there were a variety of different phone numbering systems in use across North America – each local area was responsible for defining its own system for numbering, based on the needs of local subscribers. This wasn’t ideal as the various local phone networks became interconnected, and as people wanted to place long distance calls.
So in 1947, AT&T published the first version of the NANP. The system was designed to divide North America into a series of geographic regions, with each region assigned a three-digit area code. These area codes would be followed by a three-digit exchange code and a four-digit subscriber number, creating a 10-digit phone number that could be used to reach any phone in North America.
In the early days, a key factor when selecting a phone number was speed of dialing with a rotary phone, so all the original NPAs had a zero or one as the second digit because it was easier to dial. Two of the “best” area codes were 202 and 212 because they were quick prefixes to dial. These area codes went to Washington DC (no comment…) and New York City (the most populated city), respectively. New Jersey got 201… perhaps because that’s where AT&T and Bell Lab were headquartered.
Development of the NANP
The first area codes were implemented in 1947, and by 1951, the entire United States and Canada had been divided into 86 area codes. Over time, the number of area codes continued to increase as the population of North America grew and more people began using telephones.
As the number of area codes increased, the NANP underwent several revisions to accommodate new technologies and changing population patterns. At the time the NANP was introduced, all long distance calls were made via an operator, but starting in 1951 direct distance dialing began to be tested, which allowed people to make long-distance calls without the assistance of an operator.
In fact, the very first direct distance dialed call was from made from New Jersey to the mayor of Alameda, CA (which is where I live – so I got quite a surprise as I was researching this article!).
In the 1990s, the explosive growth of the internet and mobile phones led to a surge in demand for phone numbers. To address this, NANPA decided to allow any number as the second digit of the NPA, which allowed the system to accommodate up to 800 new area codes, providing a solution for years to come.
Current status of the NANP
The NANP system has proven to be a durable and effective way of managing phone numbers in a large, geographically diverse region. However, there’s an ever increasing demand for phone numbers – due to VoIP and mobile providers. In 2022 NANPA announced 20 new NPA overlays to add numbers to existing regions – but we’re a long way from running out. As I write, there are 335 geographic and non-geographic area codes in use, so we still have hundreds available.
But of course, it’s this continual addition of new numbers that necessitates regular updates to your switch translations (along with updates to tandem switches and routes). The only way to stay on top of all this, and make sure your subscriber’s calls get through and are billed correctly, is to keep on top of the latest changes in the LERG… and of course we’d be delighted to help you with that!
