Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 857 [Rate centres in NPA 857] [Dial plan for NPA 857]

NXX: 434

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
857-434 A Cambridge MA   0051 SHELCOMM 128   2026-06-25   

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

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