Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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Switch: WTTWSDCO0MD

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
605-438 A Milbank SD 907D INTERSTATE TELECOMMUNICATIONS COOPERATIVE, INC. 640      
605-621 A Madison SD 907D INTERSTATE TELECOMMUNICATIONS COOPERATIVE, INC. 640      

Last updated: Tue, 13 Jan 2026 21:50:02 UTC

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