From 1958 to 1999 the southern part of New Jersey was served by area code 609. In 1999 the Numbering Plan Area 609 was split into two with the new area code 856 covering the south-western portion of NJ. Today, once again, a relief plan is needed for area code 609. The approved relief method is an overlay code which will serve the same south eastern NJ area currently covered by NPA 609. The new area code 640 will enter service next year in September. As a result of the newly created overlay complex 609/640, 10 digit dialing will be mandatory for all calls within its borders.
- January 20, 2018 – permissive 10 digit dialing begins (10 digit dialing is encouraged)
- August 18, 2018 – mandatory 10 digit dialing begins
- September 17, 2018 – area code 640 enters service
7 digit calls between 609 and 856 to be eliminated
Since the 1999 split of NPA 609 some calls between area codes 609 and 856 could be dialed using 7 digits. With the above changes these protected NXX codes will also be eliminated and regular 1+10 digit dialing will be required for all calls between the two NPAs.
See official NANPA announcement and map of the new overlay complex (PDF document)