Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 303 [Rate centres in NPA 303] [Dial plan for NPA 303]

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NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
303-999 5 Denver CO DNVRCOMD4MD  6010 NEW CINGULAR WIRELESS PCS, LLC 656   2008-06-01   
303-999 6 Denver CO DNVRCOMD4MD  6010 NEW CINGULAR WIRELESS PCS, LLC 656   2008-06-01   
303-999 7 Denver CO DNVRCOMD4MD  6010 NEW CINGULAR WIRELESS PCS, LLC 656   2008-06-01   
303-999 8 Denver CO DNVRCOII3MD  6529 T-MOBILE USA, INC. 656   2008-06-21   
303-999 9 Denver CO DNVRCOII3MD  6529 T-MOBILE USA, INC. 656   2008-06-21   

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Last updated: Wed, 04 Mar 2026 03:00:52 UTC

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