DAN@gacvx2.gac.edu (Dan Boehlke) (11/24/90)
Greetings, 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? Thanks. Dan Boehlke Internet: dan@gac.edu Campus Network Manager BITNET: dan@gacvax1.bitnet Gustavus Adolphus College St. Peter, MN 56082 USA Phone: (507)931-7596
SABAHE@macalstr.edu (Arun Baheti <SABahe@Macalstr.EDU>) (11/26/90)
The way I used to do it when I ran a BBS is just to have the modem do it for you. On my trusty US Robotics Courier, I just used the Hayes command set to get the phone "off hook" and I left it there until I was done with the line. ab
BRUCE@ccavax.camb.com (Barton F. Bruce) (11/26/90)
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.
ropg@ooc.uva.nl (Rop Gonggrijp) (11/27/90)
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. It's even simpler: just short the phone wires (tip and ring) and presto. >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? 1000 ohms definitely sounds too high. If you insist on using a resistor, use 10 ohms instead. The switch itself limits the current to about 20-50 mA so there should be no problem. Always play with toys they tell you not to play with..... ;*) Rop Gonggrijp (ropg@ooc.uva.nl) is also editor of Hack-Tic (hack/phreak mag.) Postbus 22953 (in DUTCH) 1100 DL AMSTERDAM tel: +31 20 6001480
system@hale.UUCP (System Administration) (11/27/90)
> 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? When I need to busy out a port, I just dial out to the port's own number, at least in my area, this will busy the line (since the line is off hook, and the number being dialed will always be busy. I'm not sure how your hunt works, but here, only the original number will forward into the group, so if you call a number in the middle of the group, it is not forwarded. I guess this couldn't be used on the main number, as you'd get forwarded to your next port. System Administrator Hale Telecommunications Public Access system@hale.uucp 619-660-6734 8N1 1200-2400 USENET UUCP SYSOP SUPPORT
Tad.Cook@beaver.cs.washington.edu (11/27/90)
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 MCI Mail: 3288544 Telex: 6503288544 MCI UW USENET:...uw-beaver!sumax!amc-gw!ssc!tad or, tad@ssc.UUCP
brian@ucsd.edu (Brian Kantor) (11/28/90)
In article <69299@bu.edu.bu.edu>, DAN@gacvx2.gac.edu (Dan Boehlke) wrote: > What is the best way to busy a phone line? I have a bank of modems Our modem lines all enter on RJ21 "punchblocks" so I've got some rather nice clips that can be pushed over the terminals on the blocks and make contact with the pair that I want to busy out. Between the two terminals on the clip I have a red LED and a 270 ohm 1/2w resistor in series. As long as I get the clip on the right way, it busies out the line and lights up so I can see that I've got one of the lines busied out. Since most of our modems have error correction, I've even gotten away with putting one of these on a line that's in use -- when the user disconnects, the line remains busy and I can then pull the modem at my leisure. The modem's error correction fixes the blast of noise from the clip as I slip it in. Brian