Area Code Atlas

NPA 610 assigned for Canadian TWX service

Area code 610 was assigned in 1962 for conversion to dial service of the Teletypewriter Exchange Service (TWX) in Canada. This use was non-geographic and separate from the later Pennsylvania geographic assignment.

Teletypewriter services reassigned from area code 610 to 600

Teletypewriter services previously provisioned with area code 610 were reassigned to area code 600 in 1993, returning 610 to the pool of unassigned area codes for general purposes. This change centralized specialized non-geographic services under the new 600 code.

Introduction of area code 600 in Canada for non-geographic services

Area code 600 was introduced on April 15, 1993, as a non-geographic code for specialized telecommunication services in Canada. The code was established to support applications such as telex, ISDN, and mobile satellite communications, particularly in remote regions where conventional infrastructure was unavailable, replacing the previous use of area code 610 for teletypewriter services.

Boundary adjustment between 215 and 717

In 1994, a few towns in eastern Lancaster County and western Chester County originally slated to transfer to area code 610 were instead shifted to area code 717 to consolidate non-Bell company subscribers in eastern Pennsylvania.

Area code 610 reassigned to Pennsylvania

Area code 610, having been returned to the pool of unassigned codes in 1993, was reassigned in 1994 to serve Pennsylvania in the United States as a general purpose area code after being previously used for teletypewriter services in Canada.

Area code 610 split from 215

Area code 610 was placed in service on January 8, 1994, as a geographic split from area code 215. The new code covered eastern and southeastern Pennsylvania, including the Lehigh Valley and Philadelphia suburbs, while 215 continued to serve the Philadelphia core.

Area code 610 in service

Area code 610 was placed in service on January 8, 1994, as an overlay for southeastern Pennsylvania, following a split from area code 215 in 1947. It covers regions including Allentown, Bethlehem, and Reading.

Mandatory dialing for 215 and 610

Permissive dialing for both area codes 215 and 610 ended on January 7, 1995. After this date, callers were required to use the correct area code for calls within the affected regions.

Extraordinary NPA-Specific Conservation Procedures for 610 NPA (Pennsylvania)

NANP-Overlay of 610 (Pennsylvania) Numbering Plan Area (NPA) with 484 NPA

Area code 484 added as overlay

Area code 484 was introduced as an overlay for the 610 region on June 5, 1999, to accommodate regional growth in southeastern Pennsylvania. This change was implemented to address number exhaustion and required the introduction of mandatory ten-digit dialing for all calls within the region.

Mandatory ten-digit dialing for 610 and 484

Mandatory ten-digit dialing was introduced in the 610 and 484 area codes on June 5, 1999, coinciding with the activation of the 484 overlay.

Extraordinary NPA-Specific Jeopardy Conservation Procedures Announced for 484 and 610 NPAs (Pennsylvannia)

NPA 835 established for 610/484 overlay

The Pennsylvania Public Utility Commission established area code 835 in May 2000 as an additional overlay for the 610/484 region. The new code was intended to be implemented in 2001 to provide additional numbering resources.

Consensus reached for overlays 445 and 835

On May 18, 2000, the Pennsylvania telecommunications industry reached consensus to implement area code 445 as an overlay for NPAs 215 and 267, and area code 835 as an overlay for NPAs 610 and 484.

NPA 445 to Overlay NPAs 215 and 267 (Pennsylvania)NPA 835 to Overlay NPAs 610 and 484 (Pennsylvania)

Correction to Assignment Procedures for the Remaining Central Office Codes in 215 and 267 NPAs, and in the 610 and 484 NPAs (Pennsylvania)

Plans for NPA 835 withdrawn

The Pennsylvania Public Utility Commission formally withdrew plans for the 835 overlay in the 610/484 area codes on June 23, 2005, after number conservation measures and number pooling eliminated the immediate need for a new overlay. The 835 code remained reserved for future use.

NPA 835 approved for 610/484 overlay complex

Area code 835 was approved by the Pennsylvania Public Utility Commission on December 2, 2021, to provide additional numbering resources for the 610/484 overlay complex, responding to projected number exhaustion.

NPA 835 overlay on 484/610 announced

NPA 835 to Overlay NPA 484/610 (Pennsylvania)

NPA 835 activated for 610/484 overlay complex

Area code 835 was activated on September 2, 2022, with assignment of central office codes beginning in the 610/484 overlay region in Pennsylvania.

Area code 835 assigned

Area code 835 was approved on December 2, 2021, and began assignment on September 2, 2022, as an overlay for the 610/484 region in Pennsylvania.