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: 443 [Rate centres in NPA 443] [Dial plan for NPA 443]

NXX: 581

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
443-581 A Chase MD BLTMMDCH42Z  876D ONVOY, LLC - MD 238      
443-581 0 Chase MD BLTMMDCH42Z  876D ONVOY, LLC - MD 238   2021-03-04   
443-581 1 Chase MD BLTMMDCH42Z  876D ONVOY, LLC - MD 238   2021-03-04   
443-581 3 Chase MD BLTQMD018MD  145J TERRA NOVA TELECOM INC. 238   2024-09-12   
443-581 5 Chase MD BLTMMDCHXUX  624H ONVOY SPECTRUM, LLC 238   2021-02-24   
443-581 6 Chase MD   2593 CORE COMMUNICATIONS, INC.- MD 238   2019-07-30   
443-581 7 Chase MD   2593 CORE COMMUNICATIONS, INC.- MD 238   2019-07-30   
443-581 8 Chase MD BLTMMDCH40Z  6855 OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 238   2019-07-06   
443-581 9 Chase MD   2593 CORE COMMUNICATIONS, INC.- MD 238   2019-04-30   

Last updated: Tue, 15 Jul 2025 18:46:49 UTC

Sponsored by: Execulink Telecom

Like this site? We accept donations via PayPal.