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: FTBNMTXCDS0

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
406-353 A Harlem MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-374 A Moore MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-383 A Dodson MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-423 A Hobson MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-473 A Judith Gap MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-566 A Stanford MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-567 A Denton MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-622 A Fort Benton MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      
406-737 A Geraldine MT 3310 TRIANGLE TEL. COOP. ASSN., INC. 648      

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

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