What the Terms "LATA", "LRN", and "Overlay" Mean


Chase Greiser


Let’s go over a few standard industry terms you may encounter while working with Bandwidth. Specifically, we will focus on LATA, LRN, Overlay and Exhausted NPA and how they apply to what we do.

LATA: Stands for Local Access and Transport Area, which is the geographic area in which numbers are routed.  Typically, LATAs do not cross states.  A state can have anywhere from one LATA, to more than ten depending on its population.
  For example: the state of Louisiana has four LATAs: 486, 488, 490, and 492.  You may find LATAs valuable when ordering numbers.  If you place an order utilizing LATA, your search is narrowed to boundaries of that geographical area.
LRN: Stands for Local Routing Number, this is a unique phone number that tells the industry how to route calls.  You may come across this term when porting numbers into Bandwidth.
  Each carrier has at least one LRN per LATA.  LRNs were created to provide local number portability by allowing numbers to route successfully when moved between carriers. Local number portability (LNP) is the ability of a telephone customer in the United States to retain their telephone number if they switch to another carrier.
Exhausted NPA:  NPA is also known as an area code.  Exhausted NPAs are area codes in which almost all resources are in use and the industry no longer has available numbers in these area codes.  The only way to obtain numbers in exhausted area codes is through recycling.
  Bandwidth recycles disconnected numbers through an aging process before making them available again.  You may place a back order for an exhausted area code, however, Bandwidth cannot guarantee fulfillment and orders that have not filled after 90 days will be cancelled.
Overlay:  This is an area code that is added to a region already serviced by another area code.
  When an Overlay is added, calls must be made with ten digit dialing rather than seven.  If you’re trying to order new telephone numbers in a desirable area code, you may find there are limited quantities available.  In this case, expanding your search with an Overlay can be incredibly helpful.
  For example: in the year 2010, the New York City area code 212 became exhausted.  To provide relief, the industry added 917 and 646 as Overlays, bringing new available numbers to the area.  All of these area codes service the same geographic region as 212.


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