NPA Exhaust
NANP · also called area code exhaust, NPA exhaustion
The point at which an area code runs out of assignable central-office codes, triggering relief planning.
Exhaust is the projected point at which an area code will have no more assignable NXX codes left to allocate. NANPA publishes exhaust projections (roughly twice a year) for every NPA, based on assignment history, carrier forecasts and pooling behavior.
A projection is a moving estimate to quarter precision, not a fixed date — it is revised each cycle as capacity is consumed or recovered. Relief planning generally begins years before the projected exhaust.
Exhaust is about running out of prefixes to assign, not about every phone number being in use. Pooling stretches capacity within assigned codes, so prefix exhaust and number-level usage are different things.
Every area code page on NumberResearch shows this in practice — assigned prefixes, thousands-block breakdown and exhaust forecast. For example: area code 626 ↗.