Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 603 [Rate centres in NPA 603] [Dial plan for NPA 603]

NXX: 597

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
603-597 A Lyme NH MNCHNHACDS0  7778 MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NH 122      
603-597 1 Lyme NH MNCHNHCOX9Z  637E ONVOY, LLC - NH 122   2023-08-20   
603-597 6 Lyme NH   145J TERRA NOVA TELECOM INC. 122   2026-07-04   
603-597 8 Lyme NH   145J TERRA NOVA TELECOM INC. 122   2025-10-31   
603-597 9 Lyme NH MNCHNHACDS0  7778 MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NH 122      

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

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