Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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Keystone, SD

NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date
605-666 A KYSTSDXADS1  1660 FORT RANDALL TELCO DBA MT RUSHMORE TELEPHONE CO 640      

Last updated: Wed, 18 Jun 2025 02:30:00 UTC

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