On 02-Apr-12 18:27, Nobody wrote:
It intrigues me as to why North America cannot go to area code +
eight-digit addressing. Theoretically, you're increasing the number
availability by ten but don't have to create a new area code.

Changing the length of our phone numbers has many repercussions and will
not be undertaken until there is no other option. Adding new area codes
here and there is seen as the less painful solution in the short term,
and politicians rarely consider anything beyond the next election.

However, technical planning for expanding our numbers from ten to eleven
or twelve digits has already been done, for use when all other options
have been exhausted.

Note that our current ten-digit scheme allows for nearly 6.4 billion
phone numbers, which would be plenty for the 400 million people living
within the NANP if they weren't assigned so inefficiently.

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

On Apr 2, 8:05*pm, Stephen Sprunk wrote:

Note that our current ten-digit scheme allows for nearly 6.4 billion
phone numbers, which would be plenty for the 400 million people living
within the NANP if they weren't assigned so inefficiently.

It amazes me that dedicated outward trunks of a PBX get dialable
numbers even though no on ever calls them. They should get specially
identified numbers (eg in the 1nn-xxxx series) so they don't waste
addressable numbers. Actually, inward trunks to a PBX really need
only one addressable number, all the hunt lines could be a special
series, too.

Heck, I think even in panel days a hunt group didn't need to be
consecutively numbered lines, only step demanded that.

wrote:
On Apr 2, 8:05*pm, Stephen Sprunk wrote:

Note that our current ten-digit scheme allows for nearly 6.4 billion
phone numbers, which would be plenty for the 400 million people living
within the NANP if they weren't assigned so inefficiently.

It amazes me that dedicated outward trunks of a PBX get dialable
numbers even though no on ever calls them. They should get specially
identified numbers (eg in the 1nn-xxxx series) so they don't waste
addressable numbers.

Oh, c'mon. Then you'd need to program mechanical and electro-mechanical
devices to recognize phone numbers in different ways.

As there are almost always plenty of line numbers available for assignment,
what you suggest would have only negligible impact on the life of area
codes, and only in very limited areas.

On 02-Apr-12 21:29, wrote:
On Apr 2, 8:05 pm, Stephen Sprunk wrote:
Note that our current ten-digit scheme allows for nearly 6.4 billion
phone numbers, which would be plenty for the 400 million people living
within the NANP if they weren't assigned so inefficiently.

It amazes me that dedicated outward trunks of a PBX get dialable
numbers even though no on ever calls them.

PBX trunks aren't numbered. However, key systems ("KTS"), which many
people mistakenly call PBXes, use normal POTS lines, not trunk circuits.
Some telcos had the ability to give multiple POTS lines the same
number, but others apparently did not--and I'm not sure how recently
that came about.

They should get specially
identified numbers (eg in the 1nn-xxxx series) so they don't waste
addressable numbers.

YXX exchanges are reserved for internal network purposes (eg. billing);
they _can't_ be assigned to customer circuits, even though it's now
possible to dial them in areas with 10-digit local calling.

I'm not sure what, if anything, YXX area codes are used for; they're not
dialable by _anyone_ on a land line.

Note that the lack of YXX exchanges is key to the planned scheme to
extend phone numbers: ABC-DEF-GHIJ will become ABC-1DEF-GHIJK (except in
Canada, where it will become ABC-0DEF-GHIJK). Once the transition is
over, and everyone is dialing 12 digits all the time, the fourth digit
will change from Y to X.

Actually, inward trunks to a PBX really need only one addressable
number, all the hunt lines could be a special series, too.

Heck, I think even in panel days a hunt group didn't need to be
consecutively numbered lines, only step demanded that.

The practice had ossified by the time it was no longer a technical
requirement. Even today, hunt groups up to 10 lines usually have a
pilot number ending in 0, and hunt groups up to 100 lines usually have a
pilot number ending in 00.

PBXes don't need (telco) hunt groups, though; trunk circuits can accept
dozens of calls to the same number. (Telco) hunt groups are only used
for KTSes.

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

Stephen Sprunk wrote:

PBX trunks aren't numbered.

If outbound trunks aren't numbered, how does ANI work?

On 03-Apr-12 14:49, Adam H. Kerman wrote:
Stephen Sprunk wrote:
PBX trunks aren't numbered.

If outbound trunks aren't numbered, how does ANI work?

For a trunk, both called and calling number are explicitly signaled at
the start of each call in either direction.

Inbound calls to a number (or set of numbers, eg. DID) are routed to any
available trunk in the trunk group.

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

Stephen Sprunk wrote:
On 03-Apr-12 14:49, Adam H. Kerman wrote:
Stephen Sprunk wrote:

PBX trunks aren't numbered.

If outbound trunks aren't numbered, how does ANI work?

For a trunk, both called and calling number are explicitly signaled at
the start of each call in either direction.

So they are numbered.

Inbound calls to a number (or set of numbers, eg. DID) are routed to any
available trunk in the trunk group.

Right. ANI must be passed along to the PBX so it knows what extension
to connect to.

On 04-Apr-12 03:14, Adam H. Kerman wrote:
Stephen Sprunk wrote:
On 03-Apr-12 14:49, Adam H. Kerman wrote:
Stephen Sprunk wrote:
PBX trunks aren't numbered.

If outbound trunks aren't numbered, how does ANI work?

For a trunk, both called and calling number are explicitly signaled at
the start of each call in either direction.

So they are numbered.

There is not a 1:1 correspondence between trunks and numbers, as there
is with POTS lines. That is what makes them trunks!

If I have a block of 1000 directory numbers, all of them are routed to
the entire trunk group, so no trunk can be said to have any particular
number. Same if I only have one (high-volume) number: it is routed to
the entire trunk group, so all trunks have the "same" number, which also
means they don't have unique numbers.

Of course, trunks still have _circuit_ numbers for tracking and billing
purposes, but those are not dialable _directory_ numbers, which is what
we were discussing. For POTS lines, the directory number _is_ the
circuit number.

Inbound calls to a number (or set of numbers, eg. DID) are routed to any
available trunk in the trunk group.

Right. ANI must be passed along to the PBX so it knows what extension
to connect to.

DNIS (called number) is the opposite of ANI (calling number). The very
_need_ to signal the called number proves the trunk itself doesn't have
a fixed directory number. If it did, there would be no need for DNIS!

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

On Apr 3, 3:45*pm, Stephen Sprunk wrote:

It amazes me that dedicated outward trunks of a PBX get dialable
numbers even though no on ever calls them.

PBX trunks aren't numbered. *However, key systems ("KTS"), which many
people mistakenly call PBXes, use normal POTS lines, not trunk circuits.
*Some telcos had the ability to give multiple POTS lines the same
number, but others apparently did not--and I'm not sure how recently
that came about.

Many large PBX outward trunks are numbered with a regular phone
number.




They should get specially
identified numbers (eg in the 1nn-xxxx series) so they don't waste
addressable numbers.

YXX exchanges are reserved for internal network purposes (eg. billing);
they _can't_ be assigned to customer circuits, even though it's now
possible to dial them in areas with 10-digit local calling.

It doesn't matter what specific coding is used, the point is that they
shouldn't waste dialable numbers on lines no one would ever call.
They could assign some sort of special billing/maintenance code to
such lines.