By Peter Lyle DeHaan , PhD
As telephone numbers are assigned, the availability of numbers within an area code diminishes. In order to make sure that there are always numbers available, usage is analyzed, number exhaustion dates are projected, and steps are taken to provide for more numbers.
Although short-term steps can be taken to deal with and respond to this, the long-term solution is either an area code split or an area code overlay. Both methods accomplish the same goal of making more numbers available; however, each has its own set of strengths and weaknesses.
An area code split means that the geographic region of the area code is divided in two. One part will keep the same area code, while the other section must switch to a new area code (but everyone will retain their seven-digit number). There is a transition period for this, called permissive dialing, in which either the old or new area code can be dialed for the effected section. After a time, mandatory dialing goes into effect. At this point, any call to the new region using the old area code will not go through. These numbers eventually become available for reuse. Splits are not popular with businesses, as it requires printing new stationary, changing all advertising, and many other changes, including reprogramming phone systems. (In rapidly growing areas, to avoid the need to repeat this process in a few years, sometimes a three-way split is made at the same time. This divides an area into three sections, one retaining the original area code and the other two each getting their own new area code.)
An area code overlay means that a new area code is assigned to the same geographic region as the existing code(s), which is running out of numbers. With an overlay, no one needs to change area codes. However, if it is not already implemented, ten-digit dialing becomes required for all calls, even local numbers. All new number assignments are in the new area code. As such, ordering a second line could result in a number with a different area code. Overlays are not popular with most consumers, as they do not want to dial ten digits on every call, nor remember different area codes for friends and neighbors.
If you are in area that is running out of phone numbers, you can expect your local phone company to provide ample notification in the form of letters or bill inserts, giving you time to make the needed plans and adjustments. However, do not expect to be notified of changes outside of your area code. Therefore, if your area code changes, it is up to you to notify those who call you from outside your area. Likewise, others will need to notify you should their area code change.
Dealing with new or changing area codes is not easy or enjoyable, but it is necessary to ensure that there is an adequate supply of numbers for future growth.