Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
  • Effective date searches are available only for US area codes. Our sources for non-US NPA-NXX data do not provide this information.
  • If you want to search an entire area code regardless of activity, leave both the next and past days fields set to zero.

OCN: 008A MOUNTAINET TELEPHONE COMPANY - TN

NPA-NXX BLOCK Rate Centre Region Switch LATA LIR Eff date Disc date
423-256 5 Church Hill TN   956   2004-10-08   
423-389 7 Midway (Sullivan) TN   956   2004-10-01   
423-578 7 Kingsport TN   956   2003-08-25   
423-579 1 Kingsport TN   956   2009-04-06   
423-979 8 Johnson City TN   956   2004-01-30   

Last updated: Thu, 29 Jan 2026 14:35:03 UTC

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