Area Code Update
On July 1, 1999, Manhattan got a new area code, 646. Current customers keep the same area code, but any customers who order new service, add an additional line, or move may be assigned the new 646 area code where 212 or 917 numbers are unavailable.

An overlay is a new way of expanding the number of available telephone numbers in an area by placing a new area code "on top of" the existing area code. A new area code is simply added to the same geographic region where an existing area code already works, meaning that two area codes work in the same area. Only new phone lines and new telephone numbers get the new area code, so no existing telephone numbers have to change.