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.

Switch: PHLAMOXARS0

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
573-439 A Philadelphia MO 1914 MARK TWAIN RURAL TEL. CO. 520      
573-478 A Durham MO 1914 MARK TWAIN RURAL TEL. CO. 520      
573-853 A Williamstown MO 1914 MARK TWAIN RURAL TEL. CO. 520      

Last updated: Thu, 05 Feb 2026 23:41:55 UTC

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