Within a given scheme of area codes and local phone numbers, only so many combinations are available. Moreover, millions of telephone users must reprogram themselves , often unlearning some of the dialing habits they've known for generations. Ironically, while phone numbers themselves have limits, so do the means of freeing up phone numbers.
Some approaches make more sense than others in specific cases, and most involve tradeoffs.
A new and an old area code share exactly the same space. The original plan called for area code 646 to be overlaid on 212 in April 1998, but with 7-digit dialing continuing for calls with the same area code. The NY-PSC applied for a waiver, which was denied but is again under review. The overlay of 718 with 347 is scheduled for October 1, 1999. Altering the area-code format .