Area code

Non geographic

Non geographic code, in service since 2017-09-21. Part of the 500/533/544/566/577/588/521/522/523/524/525/526/527/528/529/532/538/542 overlay complex — ten-digit dialing required.

Split from 500. Overlaid with 500, 522, 523, 524, 525, 526, 527, 528, 529, 532, 533, 538, 542, 544, 566, 577, 588 .

Statusin service

Introduced2017-09-21

Local dialingNA

Time zoneEastern

Last verified2026-09-17

Change history

Recorded events for this NPA

2017-09-21 Assignment of NPA 521 for Non-Geographic Services. new npa
2017-09-21Area code 521 entered service (created from 500).

Planning letters & orders

Primary documents

NANPA planning letters for area code 521
Date	Document	Subject
2017-09-21	PL-511 ↗	Assignment of NPA 521 for Non-Geographic Services.
2017-03-24	PL-505 ↗	Assignment of NPA 521 for Non-Geographic Services

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