Local Calling Guide

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NPA: 571 [Rate centres in NPA 571] [Dial plan for NPA 571]

NXX: 521

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
571-521 A Herndon VA   829J PAETEC ITEL, LLC 236   2025-04-02   
571-521 1 Herndon VA   829J PAETEC ITEL, LLC 236      
571-521 3 Herndon VA MCLNVA23DS4  8825 LEVEL 3 COMMUNICATIONS, LLC - VA 236   2020-08-21   
571-521 4 Herndon VA VINNVACBDS0  138E ONVOY, LLC - VA 236   2024-12-13   
571-521 6 Herndon VA   829J PAETEC ITEL, LLC 236      
571-521 7 Herndon VA WASHDCINDS0  7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236   2006-03-07   
571-521 8 Herndon VA MCLNVA23DS4  8825 LEVEL 3 COMMUNICATIONS, LLC - VA 236   2006-05-11   
571-521 9 Herndon VA WASKDCFNAMD  6827 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - VA 236   2006-04-27   

Last updated: Tue, 16 Jun 2026 00:09:45 UTC

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