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From: BRUCE@ccavax.camb.com (Barton F. Bruce)
Newsgroups: comp.dcom.telecom
Subject: Re: Keeping a Line "Busy" Without a Phone Off Hook
Message-ID: <14943@accuvax.nwu.edu>
Date: 26 Nov 90 02:38:24 GMT
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X-Telecom-Digest: Volume 10, Issue 845, Message 5 of 14


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

The 120 ohm 5 watt resistor typically used for a key system hold
should do.  Old Rixon modem cages we have in racks all used 200 ohm 2
watt resistors.

If your loop is short, you may get up near 100 ma, and a long loop
will seldom go below 23 ma which is the lower limit for many TT dials.
You need enough current flowing for the CO to think you are off hook.
15 ma should do it, but by 25 you are safe. Just be sure your resistor
can handle the heat.

I used to be 'nice' and use a resistor, but tend to simply short the
line these days. Our NYC office for years would busy ALL LINES except
the first (which had the answering machine) by having the receptionist
flip a switch 'to turn on the answering machine' as she left. A 12
pole wire spring relay in the KSU did the rest, and was simply
shorting the lines.  This config also lit her hold button, just to
remind her to switch it off in the morning.

NYTel never said boo. I assume they learned to ignore any alarms
raised, or more probably never got any.

If the line you need to busy is ground start, ground the ring side, or
keeping it simple, ground BOTH sides of the line.

When there is an open wire that is THEIR fault, they generally will
busy the particular line at the CO until it gets fixed - if you make
it clear to repair that the dead line is messing up hunting. If only
one wire is open, you can still busy the line if it is the Tip side
that is open. Just treat it like a ground start line.

Another way to busy a dead line is to dial it from some spare line and
simply leave it ringing. Some smarter COs won't let this ring forever
though.