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From: hpubvwa!ssc!Tad.Cook@beaver.cs.washington.edu
Newsgroups: comp.dcom.telecom
Subject: Re: Keeping a Line "Busy" Without a Phone Off Hook
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Date: 27 Nov 90 06:42:40 GMT
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In article <69299@bu.edu.bu.edu>, DAN@gacvx2.gac.edu (Dan Boehlke)
writes:

> What is the best way to busy a phone line?  I have a bank of modems
> and from time to time I need to pull one from the pool.  Some modems
> have a "busy out" swtich.  My modems do not have a switch.  Pulling a
> modem causes the hunt to stop at modem I pulled, giving the caller a
> "no one is home" type ring.  I have heard that putting a resistor
> accross the wire is enough to hold it off hook.  If memory serves it
> was a 1000ohm resistor.  I have hesitated to do this without trying to
> learn more.  What effect does this have on the switch?  Does the
> effect varry from phone switch to phone switch?

The resistor should be a value that, when combined with the resistance
of the line, is small enough to draw at least 22 ma or so of loop
current.

But no need to use a resistor ... just temporarily short the line.
The CO will see busy, although after awhile it will cut off battery to
the line in modern digital switches.  Once you are ready to use the
line again, in some exchanges you may have to leave the line unshorted
and on hook for several minutes before the switch will test the line
and return full CO battery to it.


Tad Cook  Seattle, WA  Packet: KT7H @ N7HFZ.WA.USA.NA  Phone: 206/527-4089 
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