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: 798

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
240-798 A Gaithersburg MD VINNVACBDS0  876D ONVOY, LLC - MD 236      
240-798 0 Gaithersburg MD   5562 METROPCS, INC. 236   2021-11-01   
240-798 1 Gaithersburg MD   4036 NEW CINGULAR WIRELESS PCS, LLC - DC 236   2021-11-01   
240-798 2 Gaithersburg MD   876D ONVOY, LLC - MD 236   2021-10-31   
240-798 3 Gaithersburg MD   876D ONVOY, LLC - MD 236   2021-10-31   
240-798 4 Gaithersburg MD   516J TON80 COMMUNICATIONS, LLC 236   2021-11-01   
240-798 5 Gaithersburg MD   624H ONVOY SPECTRUM, LLC 236   2021-11-14   
240-798 6 Gaithersburg MD   624H ONVOY SPECTRUM, LLC 236   2021-11-14   
240-798 7 Gaithersburg MD   624H ONVOY SPECTRUM, LLC 236   2021-11-14   
240-798 8 Gaithersburg MD   071F BANDWIDTH.COM CLEC, LLC - MD 236   2022-08-20   
240-798 9 Gaithersburg MD   624H ONVOY SPECTRUM, LLC 236   2021-11-14   

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.