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Stephen Sprunk

On 02-Apr-12 21:25, wrote:
On Apr 2, 6:07 pm, "Adam H. Kerman" wrote:
I don't know if AT&T ever reserved area codes to any other countries for
future expansion of NANP.

Back in the _1960s_ AT&T recognized the existing area code/NNX
framework (0/1 for area codes, 2-9 NNXs) would run out and began to
program switches so that most three digit numbers could be an area
code or an exchange (as it is today). This was long before they were
actually assigned.

The original plan was that area codes would be NYN and exchanges would
be NNN (Y=0-1, N=2-9). This allowed long-distance "direct dialing" by
examining the second dialed digit: if Y, collect 8 more digits for long
distance; if N, collect 5 more digits for local.

IIRC, the issue that prompted the change was that an area code in the LA
area (213?) was running out of numbers and, rather than add a new area
code, they chose to assign NYX exchanges--breaking the scheme. This
necessitated using "1" to signify a long-distance call, which eventually
spread to the rest of the NANP. Mobile phones don't have progressive
dialing, though, so that 1 is no longer needed--and AFAIK no mobile
carrier enforces it.

There were problems when NYY and NNX area codes were added after NANPA
finally ran out of NYN area codes. NNY exchanges, which happened early
on, were a relatively minor change.

There were other patterns as well; originally, N0N was used for
states/provinces/countries with a single area code, and N1N was used for
those with multiple area codes. However, they quickly ran out of N1N
area codes and resorted to N0N area codes for the latter as well, and by
the time NYY area codes appeared, the pattern was long lost. Line
numbers starting with 9 were initially reserved for payphones, but that
rule was frequently broken and eventually disappeared, too.

S

--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking