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.

NPA: 406 [Rate centres in NPA 406] [Dial plan for NPA 406]

NXX: 993

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-993 A Big Sky MT BGSYMTXCDS0  2255 3 RIVERS TEL. COOP., INC. 650      
406-993 0 Big Sky MT   6529 T-MOBILE USA, INC. 650   2024-07-24   
406-993 1 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 2 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 3 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 4 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 5 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 6 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 7 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      
406-993 8 Big Sky MT   9415 LEVEL 3 COMMUNICATIONS, LLC - MT 650   2019-02-14   
406-993 9 Big Sky MT   2255 3 RIVERS TEL. COOP., INC. 650      

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

Sponsored by: VoIP Much Phone Company

Like this site? We accept donations via PayPal.