| 227 | Maryland (This code is scheduled to provide numbering relief to area code 240 but no date has been assigned for this to go into effect.) More information at: Area Code 227 Phone Number Blocks |
| 240 | Maryland (Hagerstown, Rockville, Cumberland and western Maryland, overlays with 301) More information at: Area Code 240 Phone Number Blocks |
| 301 | Maryland (Hagerstown, Frederick, Rockville, Cumberland and western Maryland, overlays with 240) More information at: Area Code 301 Phone Number Blocks |
| 410 | Maryland (Annapolis, Baltimore, Salisbury and eastern Maryland, overlays with 443) More information at: Area Code 410 Phone Number Blocks |
| 443 | Maryland (Annapolis, Baltimore, Salisbury and eastern Maryland, overlays with 410) More information at: Area Code 443 Phone Number Blocks |
| 667 | Maryland This Area code is scheduled to provide numbering relief to Area code 443 but no date has been assigned for this to go into effect. More information at: Area Code 667 Phone Number Blocks |
