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.