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.

San Isidro, TX

NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date
956-481 A SISDTXXARS0  2159 VALLEY TEL. COOP., INC. 568      
956-671 A HRLNTXHGXFX  508J CENTURYLINK COMMUNICATIONS, LLC 568      
956-671 7 HRLNTXHGXFX  508J CENTURYLINK COMMUNICATIONS, LLC 568   2016-07-09   

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

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.