From discuss-return-332-pavel=atrey.karlin.mff.cuni.cz@linmodems.org  Tue Sep 14 11:57:20 1999Return-Path: <discuss-return-332-pavel=atrey.karlin.mff.cuni.cz@linmodems.org>Received: from ns.crynwr.com (ns.crynwr.com [192.203.178.14])	by atrey.karlin.mff.cuni.cz (8.8.8/8.8.8) with SMTP id LAA03960	for <pavel@atrey.karlin.mff.cuni.cz>; Tue, 14 Sep 1999 11:57:18 +0200Received: (qmail 14631 invoked by alias); 14 Sep 1999 09:57:24 -0000Mailing-List: contact discuss-help@linmodems.org; run by ezmlmDelivered-To: mailing list discuss@linmodems.orgReceived: (qmail 14626 invoked by uid 0); 14 Sep 1999 09:57:21 -0000Received: from atrey.karlin.mff.cuni.cz (pavel@195.113.31.123)  by www.linmodems.org with SMTP; 14 Sep 1999 09:57:21 -0000Received: (from pavel@localhost)	by atrey.karlin.mff.cuni.cz (8.8.8/8.8.8) id LAA03752;	Tue, 14 Sep 1999 11:56:42 +0200Message-ID: <19990914115642.00867@atrey.karlin.mff.cuni.cz>Date: Tue, 14 Sep 1999 11:56:42 +0200From: Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>To: discuss@linmodems.orgCc: pavel@ucw.czSubject: Damaging telephone networkMime-Version: 1.0Content-Type: text/plain; charset=us-asciiX-Mailer: Mutt 0.84Status: ROContent-Length: 3268Lines: 67Hi!After discussions if non-homologed modem can cause damage to telephonenetwork, I decided to write file "telephone damage howto".> Telecomms regulations are taken very seriously in many countries,> because it's so important.  It's only recently that the network got> really robust, and I think only in the better developed countries.We certainly have some pretty old phone switches here, and they areundamageable, too. It is simple: lightning likes to hit phonelines. Phone switches need to survive that.You can do few nasty things to telephone network:1) Pick up 1000 phones at once on one telephone switch. You canoverload its power supply this way and it may explode. On newer phoneswitches, software likes to crash due to overload. It doesn't make anypermanent damage but the switch obviously crashes and thenautomatically recovers, which MAY render it out of service for acouple of seconds/minutes.2) Inject unallowed frequencies. These frequencies are not used exceptfor the 16kHz, which is used for transferring meter pulses to remote(subscriber's) private meter. However, it cannot be abused for makingfree calls - the switch can only transmit these frequencies, notreceive it - so it is useless to send them to it. Czech PSTN networkwas never fraudable by using tones - the only exception was to make anintrusion to the communication of other party using the 2700 Hzfrequency, generated for example by the dog's whistle.3) Dial numbers such as 13A (A is 11 pulses, for pulse dialing,special tones in DTMF.). Many interesting numbers may be found there,like all the recorded messages, special test trunks and otherfeatures.  SOMETIMES one may find a toll-free route to someinteresting destination (like international gateway) but SPT peopleare much more careful than on the beginning and such numbers are VERYrare now.4) Put a pemanent voltage (like 230V/50Hz) to the telephoneline. There were cases that the switch totally burned out (only themetallic parts remained) by connecting a fax with a broken powersupply which put the mains live wire directly to the line. The reasonis very simple: the lightning protectors of some older types open onsuch a voltage and flowing current causes their overheating. They maythen serve as a fire initiator.5) On an electromechanical switch (P51), connect some atypicalresistance to the line. The loop relay then doesn't close fully andmay switch some circuits to the unstable state with high powerconsumption. However, the fuse obviously is the only element which isdestroyed by this.6) On an electromechanical switch (P51), use VERY distorted dialingpulses. You may block the mechanism of the step-by-step selector. Thefuse will blow and the selector will need to be repaired manually.								PavelPS: If you have some corrections, additions, etc, let me know. Fromabove list, I think it is obvious telephone network is not easilydamaged. Lucent modems certainly are not capable of putting 230V/50Hzonto line. P51 switches are being slowly replaced even in our country,I do not think you can find them in developed world.-- The best software in life is free (not shareware)!		PavelGCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+