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: 240 [Rate centres in NPA 240] [Dial plan for NPA 240]

NXX: 474

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
240-474 A Gaithersburg MD VINNVACB2MD  8697 BALTIMORE-WASHINGTON TELEPHONE (BWT) 236      
240-474 0 Gaithersburg MD   876D ONVOY, LLC - MD 236   2016-03-04   
240-474 1 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2015-07-20   
240-474 2 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2015-07-20   
240-474 3 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2015-07-20   
240-474 4 Gaithersburg MD   8697 BALTIMORE-WASHINGTON TELEPHONE (BWT) 236   2015-07-13   
240-474 5 Gaithersburg MD   318J COMCAST IP PHONE, LLC 236   2015-09-30   
240-474 6 Gaithersburg MD   5562 METROPCS, INC. 236   2015-12-10   
240-474 7 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2015-10-16   
240-474 8 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2016-01-08   
240-474 9 Gaithersburg MD   876D ONVOY, LLC - MD 236   2016-03-04   

Last updated: Thu, 01 Jan 2026 03:59:49 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.