Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 503 [Rate centres in NPA 503] [Dial plan for NPA 503]

NXX: 634

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
503-634 A Monitor OR MNTRORXA0MD  2384 MONITOR COOP. TEL. CO. 672      

Last updated: Sat, 15 Nov 2025 03:38:44 UTC

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