Area Code Atlas

NPA 878 to Overlay NPAs 412 and 724 (Pennsylvania)

Permissive 10-digit dialing begins for 412 and 724

Permissive 10-digit dialing began on July 17, 2000, for calls within and between the 412 and 724 area codes in preparation for the 878 overlay. Callers could use either seven or ten digits during this transition period.

Ten-digit dialing becomes mandatory in southwestern Pennsylvania

In 2001, ten-digit dialing became mandatory across southwestern Pennsylvania due to the implementation of the 878 overlay for both 412 and 724. This change affected all customers in the region.

Rationing in NPAs 412, 724, and 878 (Pennsylvania)

Mandatory 10-digit dialing for 412 and 724

Mandatory 10-digit dialing was implemented on July 12, 2001, for all calls within and between the 412 and 724 area codes, coinciding with the overlay of area code 878. Seven-digit dialing was discontinued.

Area code 878 overlays 412

On August 17, 2001, area code 878 was implemented as an overlay for area code 412. This change was made to provide additional numbering resources for the Pittsburgh region.

NPA 878 overlay implemented for 412 and 724

Area code 878 was activated on August 17, 2001, as an all-services overlay for both 412 and 724 in southwestern Pennsylvania. This overlay required mandatory ten-digit dialing throughout the region and was implemented after both 412 and 724 faced number exhaustion.

Mandatory ten-digit dialing begins in 412, 724, and 878 simultaneously

Ten-digit dialing became mandatory in the 412, 724, and 878 numbering plan areas on August 17, 2001, coinciding with the activation of the 878 overlay to accommodate growing demand for telephone numbers in southwestern Pennsylvania.

First telephone numbers assigned for area code 878 in 412 region

In 2013, telephone numbers were first assigned for area code 878 in the 412 region, more than a decade after the overlay was implemented.

Announcement to begin issuing 878 numbers in 724 territory

The Pennsylvania Public Utility Commission announced on February 15, 2013, that it would begin assigning 878 numbers in the 724 area due to near exhaustion of available 724 numbers. This marked the first practical use of 878 numbers more than a decade after the overlay's activation.

Announcement to start issuing 878 numbers in 724 territory

The Pennsylvania Public Utility Commission announced it would start issuing 878 numbers in the 724 territory within the next year due to near exhaustion of 724 numbers.

First 878 numbers issued in 724 territory in April 2013

The first telephone numbers using area code 878 were issued in the 724 territory in April 2013 after exhaustion of available central office codes in 724. Numbers in the 412 territory were assigned later, marking the beginning of active 878 assignments in the overlay area.

First 878 numbers assigned in 724 territory

The first telephone numbers with area code 878 were assigned in the 724 territory in April 2013, nearly 12 years after the overlay was activated.

First telephone numbers assigned for area code 878 in 724 region

In 2015, telephone numbers were first assigned for area code 878 in the 724 region, completing the activation of the overlay across both 412 and 724.

First 878 central office prefix assigned in 412 territory

The first central office prefix (999) using area code 878 was assigned in the 412 territory on September 15, 2015, marking the beginning of 878 number assignments in the Pittsburgh area.

First 878 central office prefix assigned in 412 territory

The first 878 central office prefix (999) was assigned in the 412 territory on September 15, 2015, marking the start of 878 number assignments in Pittsburgh.