🚀 go-pugleaf

Rich is correct insofar as if the only issue we have to be concerned about is
the growth in subscriber lines, than the switch from N0/1X to NXX would be
more than adequate to carry us into the next century.  Switching from N1/0X
to NXX would increase the total of  available numbers in the North American
Numbering Plan (NANP) by a factor of 4 or 5.  

Whether this will in fact be enough to get us very far into the next century
depends a great deal on how the available numbers are allocated, particularly
in an environment of competitive carriers.  If we witness a proliferation of
competitive local carriers, or corporate private networks, and if each public
or private carrier must be assigned exchange codes to allocate within each
area code, then the rate at which exchange codes get "used up" (e.g.
committed) within an area code will depend more on the rate of proliferation
of carriers than on the  rate of growth of subscriber lines.  Granted that
each such assigned exchange code would be only sparsely used, but it will be
committed nonetheless.  The result could well be a need to do more than
switch to NXX for area codes in order to handle future growth.
Alternatively, we could assign "area codes" to each competitive carrier, and
let them assign exchange codes (perhaps with geographical significance like
early 800 numbers).   All it would take is for the Fortune 500 to each create
private networks and demand their own area codes, and the supply would be
quickly exhausted.

It is possible that the use of CCS and database services of the type which
support 800 numbers will allow the same area code or exchange codes to be
used by different carriers with a database look up to determine which carrier
in fact to route to.  Who would run such a database?  The information therein
would be much too sensitive to trust to a competitor such as a BOC or
AT&T.... (A similar problem occurred with the allocation of Ethernet numbers.
Originally Xerox proposed to allocate numbers in blocks of 10,000 to various
manufacturers.  You had to use up an allocation before you could ask for
more.  Needless to say, IBM did not take kindly to the idea of telling Xerox,
to the nearest 10,000, how many network connections it had sold! The IEEE 802
standard removes the allocation of numbers from Xerox.)