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.

Washington Zone 10, MD

<< 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 >>

NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date
301-284 9   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-294 A RKVLMDRVDS1  9212 VERIZON MARYLAND, INC. 236      
301-296 A WASKDCFNPS0  7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 0   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 1   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 2   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 3   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 4   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 5   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 6   318J COMCAST IP PHONE, LLC 236   2013-08-01   
301-296 7   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 8   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-296 9   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 236      
301-299 A BTHSMDBDDS0  9212 VERIZON MARYLAND, INC. 236      
301-309 A RKVLMDRVDS1  9212 VERIZON MARYLAND, INC. 236      
301-309 0   9212 VERIZON MARYLAND, INC. 236      
301-309 1   9212 VERIZON MARYLAND, INC. 236      
301-309 2   9212 VERIZON MARYLAND, INC. 236      
301-309 3   9212 VERIZON MARYLAND, INC. 236      
301-309 4   9212 VERIZON MARYLAND, INC. 236      
301-309 5   9212 VERIZON MARYLAND, INC. 236      
301-309 6   9212 VERIZON MARYLAND, INC. 236      
301-309 7   6395 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MD 236   2021-08-20   
301-309 8   9212 VERIZON MARYLAND, INC. 236      
301-309 9   9212 VERIZON MARYLAND, INC. 236      
301-315 A RKVLMDRVDS1  9212 VERIZON MARYLAND, INC. 236      
301-339 A   829J PAETEC ITEL, LLC 236   2025-04-02   
301-339 0   829J PAETEC ITEL, LLC 236      
301-339 1   829J PAETEC ITEL, LLC 236      
301-339 2   829J PAETEC ITEL, LLC 236      
301-339 3   6855 OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 236   2006-12-15   
301-339 4   6855 OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 236   2006-10-30   
301-339 5   829J PAETEC ITEL, LLC 236      
301-339 6   7591 LEVEL 3 TELECOM OF MARYLAND, LLC - MD 236   2012-03-02   
301-339 7   829J PAETEC ITEL, LLC 236   2006-12-21   
301-339 8   318J COMCAST IP PHONE, LLC 236   2012-12-01   
301-339 9   829J PAETEC ITEL, LLC 236      
301-340 A RKVLMDRVDS1  9212 VERIZON MARYLAND, INC. 236      
301-353 A GMTWMDGNDS0  9212 VERIZON MARYLAND, INC. 236      
301-354 A WASHDCTTDS0  7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 0   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 1   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 2   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 3   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 4   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 5   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 6   508J CENTURYLINK COMMUNICATIONS, LLC 236   2013-10-01   
301-354 7   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 8   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      
301-354 9   7529 TELEPORT COMMUNICATIONS AMERICA, LLC - DC 236      

<< 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 >>

Last updated: Thu, 29 Jan 2026 14:35:03 UTC

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.