myerston@cts.sri.com (11/21/89)
Several articles have appeared recently on this topic not all of
which have been particularly enlightening. This is an attempt to
clear some of the fog.
o Key Systems (KSUs, ETKTS, etc) are devices which allow X
number of users access to Y number of "outside" lines. Initially
this was done electro-mechanically by various systems of which the
AT&T 1A2 (the famous 6 button sets) is the best known. Like many
AT&T gear, the design was made public and many others, notably ITT
manufactured 1A2 besides Western Electric. 1A2s are still around,
particularly in Defense-related "secure areas" were changes take
forever (but that is another story). Electronic KSUs today do the
same functions as the 1A2 (plus many others) but use "skinny wiring"
(one or two twisted pairs) where the traditional 1A2s used 25 pair
"fat" wiring with Amphenol connectors. MOST Key Systems require a
central controller (the Key System Unit or KSU) and special
propriatary sets. MOST Key systems have direct trunk access (to grab
a line you punch a button). Key systems use standard (1MB) business
lines as trunks.
o Hybrids are a sub-category of Key Systems which typically
permit use of standard sets and substitute centralized trunk
selection for direct trunk selection (Dial 9 for an "outside line",
the switch selects which one to give you). Many hybrids provide for
both methods depending on the set used.
o Small PBXs do exactly the same thing as a hybrid KSU. Rumor
has it that, in some jurisdictions, calling a box a KSU or Hybrid
lets you use 1MBs for trunking, call it a PBX and you have to order
more expensive PBX trunks (to the CO they are the same, to the
Business Office they are not.
o Key System have model numbers in the form AAABBB where AAA is
the number of trunks it can handle and BBB the number of inside lines.
Some come fully equipped for AAA lines and BBB trunks out of box.
Others require additional cards to reach full capacity.
o Further blurring the Key Sys/Hybrid line is the fact that many
Key Systems can handle a limited number of "plain" sets with special
cards while many Hybrids require at least one propriatary set to
program.
o Modern Key Systems can do almost anything a PBX can. The list
of features available is almost mind-boggling.
Now the REAL issue. There are over 100 brands of KSUs out there.
They range from semi-PBXs to a two line, four extension model
(Panasonic PA 20810, around $270). Another big deal is how they
distribute. Many (Toshiba, Iwatsu) will only sell to interconnects
who, in turn, want to do only Turn-Key installations. Others
(Panasonic, Southwestern Bell, Inter-Tel) will sell through wholesale
outlets and parts houses like Graybar, Anixter etc. Here in CA
wholesale outlets mean they will sell one in onesis and twosis if you
have a resale license. ProcComm in San Diego and Tele-Com Products in
LA are two I have dealt with and had excellent results re: prices,
shipping etc.
Another complicator. AT&T who makes very nice and frightfully
expensive KSUs (Spirit and Merlins) went after the Japanese
manufacturers (TIE, Intertel, Extrom, Panasonic etc) for dumping.
They won their case and there is now a >> 130 to 180% << import duty
on Japanese KSUs. Korea got a 6 to 9% duty. As a result many Key
Systems are in short supply while the japanese shift production to
other places including Europe and the US. Before this you could get a
good 6 X 16 hybrid system for around $700.
Hope this helps.