Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 571 [Rate centres in NPA 571] [Dial plan for NPA 571]

NXX: 638

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
571-638 A Herndon VA WASHDCTTDS0  7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
571-638 0 Herndon VA   624H ONVOY SPECTRUM, LLC 236   2023-08-15   
571-638 1 Herndon VA   624H ONVOY SPECTRUM, LLC 236   2023-08-15   
571-638 2 Herndon VA   624H ONVOY SPECTRUM, LLC 236   2023-08-15   
571-638 3 Herndon VA   624H ONVOY SPECTRUM, LLC 236   2023-08-15   
571-638 4 Herndon VA   624H ONVOY SPECTRUM, LLC 236   2023-08-15   
571-638 5 Herndon VA   138E ONVOY, LLC - VA 236   2023-08-24   
571-638 6 Herndon VA   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236   2023-07-08   
571-638 7 Herndon VA   138E ONVOY, LLC - VA 236   2023-08-24   
571-638 8 Herndon VA   138E ONVOY, LLC - VA 236   2023-08-24   
571-638 9 Herndon VA   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2023-08-06   

Last updated: Thu, 29 Jan 2026 14:35:03 UTC

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