Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 301 [Rate centres in NPA 301] [Dial plan for NPA 301]

NXX: 378

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
301-378 A Frederick MD FRDRMDFRXTX  318J COMCAST IP PHONE, LLC 240      
301-378 0 Frederick MD   318J COMCAST IP PHONE, LLC 240   2007-04-06   
301-378 1 Frederick MD   829J PAETEC ITEL, LLC 240   2011-03-04   
301-378 2 Frederick MD   318J COMCAST IP PHONE, LLC 240   2009-08-13   
301-378 3 Frederick MD   5562 METROPCS, INC. 240   2011-07-08   
301-378 4 Frederick MD   5562 METROPCS, INC. 240   2011-07-08   
301-378 5 Frederick MD   5562 METROPCS, INC. 240   2022-11-07   
301-378 6 Frederick MD   145J TERRA NOVA TELECOM INC. 240   2022-11-07   
301-378 7 Frederick MD   7325 TELEPORT COMMUNICATIONS AMERICA, LLC - MD 240   2012-09-10   
301-378 8 Frederick MD   318J COMCAST IP PHONE, LLC 240   2012-11-03   
301-378 9 Frederick MD   318J COMCAST IP PHONE, LLC 240   2013-05-12   

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

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