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: 603 [Rate centres in NPA 603] [Dial plan for NPA 603]

NXX: 345

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
603-345 A Merrimack NH MNCHNHCOX4Z  6290 UNITED STATES CELLULAR - NH 122      
603-345 0 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 1 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 2 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 3 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 4 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 5 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 6 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 7 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 8 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      
603-345 9 Merrimack NH   6290 UNITED STATES CELLULAR - NH 122      

Last updated: Sat, 21 Mar 2026 23:53:39 UTC

Sponsored by: VoIP Much Phone Company

Like this site? We accept donations via PayPal.