Area code 878 serves the state of Pennsylvania. This area code was assigned on December 15th, 1999. On August 17th, 2001 it went into service. 878 is a General Purpose Code. 878 service area does overlap with 412 724 area codes. Dialing pattern for local calls within the same NPA (area code) is 10D. All calls within and between NPAs 412 and 724 and 878 can be dialed as 10D or 1+10D. Calls to other NPAs must be dialed as 1+10D.