Located in the Eastern (GMT -05:00) time zone. Area code 667 serves the state of Maryland. This area code was assigned on January 3rd, 2001. On March 24th, 2012 it went into service. 667 is a General Purpose Code. 667 service area does overlap with 410 443 area codes. Dialing pattern for local calls within the same NPA (area code) is 10D.