[comp.dcom.telecom] Why Are Phone Systems so *Stupid*??

"Ole J. Jacobsen" <ole@csli.stanford.edu> (08/22/90)

Why is it that most phone systems insist on "knowing" about CO lines,
*only* if these lines are properly "grabbed" by requesting extensions
on the other side of the switch? If I can buy a cheap "line status
indicator" which "knows" that a CO line is off hook, why can't the
switches use similar brain power to figure the status of CO lines?

The problem arises when you try to hook devices (modems, answering
machines, faxen, etc.) *directly* to CO lines (which are also
connected to the phone system). The phone system (stupidly) has no way
of knowing when such a line is active and will merrily grab it at
random with disastrous effects.

Please don't tell me to hook my modem into an extension port, I only
have 16, and that's not enough for a one bedroom place, besides having
to dial 9....:-)

P.S. This problem is present on both cheap systems like the Panasonic
KX-T61610 and the expensive Merlin 2. Both fail the basic intelligence
test in this respect. Arrg.


Ole J Jacobsen, Editor and Publisher  
ConneXions--The Interoperability Report    Interop, Inc. 
480 San Antonio Road, Suite 100       Mountain View, CA 94040    USA
Phone: (415) 941-3399   FAX: (415) 949-1779    ole@csli.stanford.edu

John Higdon <john@bovine.ati.com> (08/22/90)

"Ole J. Jacobsen" <ole@csli.stanford.edu> writes:

> Why is it that most phone systems insist on "knowing" about CO lines,
> *only* if these lines are properly "grabbed" by requesting extensions

> P.S. This problem is present on both cheap systems like the Panasonic
> KX-T61610 and the expensive Merlin 2. Both fail the basic intelligence
> test in this respect. Arrg.

Are you serious? What you describe is also true of the most expensive
Mitels, ITT 3100s, Meridian/SL1s, etc., etc., ad nauseum. Why on earth
should a PBX be equipped with "line status detection" when it was
never intended that a trunk would be shared with foreign equipment?
Would you dangle some gadget off of a four-wire E&M trunk and then
expect a PBX to detect it and deal with it?

A trunk to a PBX, whether it be two wire (ground or loop start) or
four wire E&M is supposed to be a trunk to a PBX and is not intended
to be shared with modems, answering machines, dialers, or any other
doodads.  Some PBXs accept trunks as T-spans. What kind of gadgetry
would you expect to be able to tack on to those circuits and have the
PBX recognize it and deal with it?


        John Higdon         |   P. O. Box 7648   |   +1 408 723 1395
    john@bovine.ati.com     | San Jose, CA 95150 |       M o o !

peter@ficc.ferranti.com (Peter da Silva) (08/24/90)

Why not stick an answering-machine-cutoff gadget on the line to the
switch that you want to put the modem on?


Peter da Silva.   `-_-'
+1 713 274 5180.   'U`
peter@ferranti.com

Beach@cup.portal.com (08/25/90)

> Why is it that most phone systems insist on "knowing" about CO lines,
> *only* if these lines are properly "grabbed" by requesting extensions

> P.S. This problem is present on both cheap systems like the Panasonic
> KX-T61610 and the expensive Merlin 2. Both fail the basic intelligence
> test in this respect. Arrg.

The Merlin PLUS has an RJ-11 on the line card to which standard
telecom stuff can be placed (modem/fax/etc).  When a device loads this
jack, by going off hook, the Merlin + busies out the associated line.

I am sure the Merlin 2 has capability to connect standard equipment
AFTER the switch.  I suspect the reason most switches don't monitor
incoming lines as you suggest is that doing so would probably cause
more problems than the mostly nonexistant need for it would benefit.


Steve Warner
fremont, CA, usa, etc