Customer Activated Malicious Call Trace

The following page and the pages it links to are old, but hopefully still relevent in principle.  They used to be at http://www.ozemail.com.au/~firstpr/mct .  By the way, see David Hickson's UL pages on the problem of "silent calls" - calls which arrive without any person or announcement to tell the recipient what the call is about: http://www.users.waitrose.com/~silentcalls/ .

ACIF has a draft code C525:2005 Handling of Life Threatening and Unwelcome Calls Industry Code:  http://www.acif.org.au/__data/page/13950/DR_C525_PUBLIC_COMMENT_DRAFT.pdf  which will result in an update to the existing code: http://www.acif.org.au/documents_and_lists/codes/C525 . 

The definition of "malicious call" is no longer in section 85ZE of the Crimes Act, it is in section 474.17 of the Criminal Code Act 1995 ( http://www.comlaw.gov.au , but try here for a PDF):

474.17 Using a carriage service to menace, harass or cause offence

(1) A person is guilty of an offence if:

(a) the person uses a carriage service; and
(b) the person does so in a way (whether by the method of use or the content of a communication, or both) that reasonable persons would regard as being, in all the circumstances, menacing, harassing or offensive.

   Penalty: Imprisonment for 3 years.

(2) Without limiting subsection (1), that subsection applies to menacing, harassing or causing offence to:

(a) an employee of the NRS provider; or
(b) an emergency call person; or
(c) an employee of an emergency service organisation; or
(d) an APS employee in the Attorney-General’s Department acting as a National Security Hotline call taker.

The section before this, 474.15 is of interest too.  It prohibits using a carriage service (eg. the phone network) to threaten to kill or seriously harm a person.  Section 474.16 concerns calls "with the intention of inducing a false belief that an explosive, or a dangerous or harmful substance or thing, has been or will be left in any place. 

A properly designed and well publicised CAMCT service would be of tremendous value for detering and detecting misuse of the phone network in many instances where the calls are not repetitive enough to be effectively traced with conventional approaches, which involve days delay to set up a trace facility:

• Bomb threats and the like, especially now that everyone is so alarmed about terrorism.
  
  
• One-off malicious calls, such as those which make the recipient fear their child or partner is dead etc.
  
  
• Convenient, legally robust, ways of tracing the source of calls which violate forthcoming Do-Not-Call legislation:  http://www.dcita.gov.au/tel/do_not_call .
  
  
• Calls which are not made with bad intent, but which are nonetheless alarming, or place an unreasonable burden on the recipient.  These include calls arising from technical malfunction in the network, and the malfunction or misuse of customer equipment such as fax machines, computerised dialling systems etc.
  

Introduction

Customer Activated Malicious Call Trace (CAMCT) is a technical facility which enables receivers of malicious calls (under the Australian Crimes Act: threatening, harassing or offensive) to quickly activate a trace of the caller. The number of the problem call is captured at the exchange and sent to investigators - it is not made available to the receiver of the call.

Australia does not at present have CAMCT for analogue phones, but all the modern exchanges of Telstra and Optus can support it. It is available, with some technical restrictions, on ISDN services - mainly corporate PABXs. The GSM phone system supports it - but it is not used here as far as I know.

Customer Activated Malicious Call Trace and the administratively clunkier "Malicious Call Trace" or "Trap" (US term) has nothing to do with Calling Number Display. Properly administered, CAMCT provides excellent deterrence against malicious calls, with few if any privacy problems. Calling Number Display (Caller ID), either on an opt-in basis (the preferable form, which has never been introduced) or on an opt-out basis, is practically useless for protecting against malicious calls or most other unwanted phone calls. CND requires special equipment and is a privacy, social and phone usage can of worms. CAMCT does not require equipment, affect normal phone usage, have negative social consequences or reduce the number of calls which are answered.

My material on Malicious Call Trace has grown over the years, and is presented here in several parts. This is not necessarily the most coherent presentation, but it is all I have time for. My work in privacy advocacy is not paid - so I can't do everything I would like to.

The focus here is on tracing malicious calls. Other kinds of unwanted calls, such as outbound telemarketing and (for some people, but generally not for me if they are genuine) market and social research calls are other common kinds of calls which cause distress and wasted time. I may expand on this later - for now, I am concentrating on calls as defined by the Crimes Act, Section 85ZE ( http://www.aust lii.edu.au/au/legis/cth/consol_act/ca191482/s85ze.html ) as threatening, harassing, or (in the circumstances, to a reasonable person) offensive.

Files in this directory

camct2.html {17 December 96} An overall description of the technical and administrative arrangements for Customer Activated Malicious Call Trace in the USA - from Joe Narun.


 mct_cnd_1996.html {17 December 96} Tabular comparison of the many differences between Customer Activated Malicious Call Trace and Calling Number Display.

Other resources

Analysis and policy

• Be sure to look at the Calling Number Display section of my WWW site, for an article on the privacy issues of the proposed CND service, a link to AUSTEL's report on CND, and some technical information about CND customer equipment standards.

• The Electronic Privacy Rights Clearinghouse in California has "How to put an end to unwanted or harassing phone calls" http://www.acusd.edu/%7E prc/fs/fs3-hrs2.html I think they are overly optimistic about the value of answering machines - malicious callers can still leave messages.

• British Telecom have some material relating to their malicious call trace operations. This is not Customer Activated Malicious Call Trace. Their approach seems to require prior arrangements, so it is only applicable to repeated calls and does not work as a general deterrent against one-off calls. http://www.bt.ne t/home/newsroom/document/nr9543a.htm Their Caller Display and their 1471 readout service for the number of the last incoming call seem to be the typical Caller ID / CND privacy and social disaster area.

• BT's August 95 press release http://www.bt.net/ home/newsroom/document/nr9543.htm reveals that the company received 1,639,741 requests for help in the battle against malicious calls in one year. This, in a population of 58 million, is no small problem. Clearly there was no effective deterrent: "more than one million individual calls made to some 65,000 customers were traced successfully at the request of the police." The introduction of Caller Display reduced complaints and hoax calls to emergency numbers by 20%. I believe that this is attributable to people fearing detection, rather than a clear understanding of what Caller Display involved - it is possible to "block" the display of the caller's number on a per line or per call basis. ("Block" is a simple but prejudicial term for making a call without the disclosure of the caller's number.) Calls to emergency numbers have nothing to do with Caller Display - and the caller's number is displayed to the operators, as it has been for many years. Callers wishing to make malicious calls need only use a payphone, or dial 141 before dialling their victim's number to ensure that their victim sees no number on their display device.

• British Telecom publishes statistics up to July 95 relating to malicious call complaints, traces, warnings, number changes (of victims) and disconnections. http://www.bt.ne t/home/newsroom/document/nr9543b.htm This is a valuable resource!

• British Telecom's Code of Practice for Consumers http://www.bt. net/home/regulate/uk/cop14/cop14-1.htm#m24 mentions that call tracing can be organised "between 8.30 am and 5 pm Monday to Friday, where call tracing may be undertaken. You should be prepared to give evidence if the malicious caller is traced, charged and brought to court." This is an interesting document for other reasons, for instance phone bills in braille or large print. I am impressed! Phone bills can also be read by humans, over the phone, to the customer before the bill is mailed.

• AUSTEL Privacy Advisory Committee's report on Calling Number Display http://lobby.auste l.gov.au/info/reports/paccnd/paccnd0.htm notes (in the Preface s Section 3, first dot point) "AUSTEL encourages carriers with fixed network service infrastructure to consider offering their directly connected customers an alternative call trace activation in conjunction with their CND service offerings."
  Section 6.3 of the report's Chapter IV http://lobby.auste l.gov.au/info/reports/paccnd/paccnd4.htm refers to Telstra's existing Malicious Call Trace facility, but says that it is basically adequate. The PAC does not recommend a more accessible tracing facility (ie. Customer Activated Malicious Call Trace) as a precondition for CND introduction, but I believe they should have. To sell people the problematic CND service (which many will be attracted to in the belief that it will be effective against malicious calls), whilst withholding CAMCT, which is essentially a free, highly effective service without privacy problems, would be a scandal. It would also be a source of increased customer complaints, decreased trust of the phone companies and do very little to deter malicious callers - who will simply make calls without allowing their number to be displayed.

• In 1994, the Public Service Commission of Wisconsin enacted a law concerning telecommunications privacy: http://www.cs.u wm.edu/faculty/levine/telecom.priv/rule.html and http://www.cs .uwm.edu/faculty/levine/telecom.priv/report.html "Every telecommunications utility shall offer to its customers a tracing service to identify the source of unlawful, abusive and nuisance telephone calls. The utility may establish a reasonable charge for the services." They also established a 13 member telecommunications privacy council. There are provisions for reviewing any new service offering for its privacy impact.

• Police detectives from Mankato in Minnesota, in their 1995 report: http://www.ic.mankato.mn.us/reg9/kato/safety/reports/review95/police2.html state: "Our ability to deal with nuisance phone calls has increased this year with the advent of the Customer Originated Trace (COT), a feature all customers of MCTC now have on their phones. This allows the customer to trace nuisance calls. The phone numbers and the time of each call is tracked on a computer in the detective's office. Through the use of this valuable feature we were able to track down a female who had phoned in numerous bomb threats to the McDonald's restaurant on Madison Ave."

• Proceedings of the Massachusetts Department of Public Utilities, including testimony from the Boston Computer Professionals for Social Responsibility, regarding Caller ID introduction in 1991: http://www.cpsr.org/dox/program/caller- id/cpsr_testimony_boston_cnid_hear.html includes "The claim that Calling-Phone ID is the only, or best, way to reduce these calls is false. Common- sense tells us that the most effective deterrent to crank calls is for would-be perpetrators to know their identity can be determined easily by the authorities. The best way to accomplish this is not to offer Calling-Phone ID but to make another service, Call Trace, widely available and easily affordable."

• The ITU has a "Recommendation I.251.7 (08/92) - Malicious call identification" available from http://info.itu.ch/itudo c/itu-t/rec/i/i251-7_23157.html with credit card payment of 20 Swiss Francs (According to http://www.xe.net/currency/ this is nearly Australian $20.) It is a 97 k byte Word document and I am not yet sure what it deals with.

• Telstra does not offer Customer Activated Malicious Call Trace (except on ISDN services) - only a more cumbersome approach which must be activated after a complaint by a customer, if resources are available and if it is thought that the problem is serious enough and that calls are likely to persist. A document outlining Telstra's expectations of its customers and the company's responsibilities to its customers is at: http://w ww.telecom.com.au/connections/guide/section4.htm#sect4b4 Its good to see a clear statement of expectations and responsibilities. Unfortunately the company's Privacy Protection Policy (which covers intrusion) is not yet available on the web.

Telcos offering Customer Activated Call Trace

• See the above links to British Telecom. The following are some of the companies I found with an Alta Vista search on 30 November 1996. There would be other telcos who do not have English language WWW sites who also offer CAMCT.

• Cambridge Cable is a smaller telephone and cable TV company in the UK. I am not sure that offer telephony via special interfaces to HFC cable as Optus Vision does. In the past "cable" telephone companies in the UK used a separate twisted pair into the home - so it was standard analogue telephony. http://www.camcable.co.uk/before. html indicates that they offer Customer Activated Malicious Call Trace. There is no mention of Caller Display or any equivalent to BT's 1471 last call number readout service.

• A local phone company in Rochester, New York State, USA offers CAMCT ("Call Trace" for the Annoyance Call Bureau) with a US $1.50 activation fee: http://www.fron tiercorp.com/rochestertel/contact/reach.html "Call Tracing should be used to trace calls that are life-threatening or harassing in nature; calls for which you might want to press legal charges. You will not receive the telephone number of the call you trace. A $1.50 fee applies for each call successfully traced." http://www.frontie rcorp.com/rochestertel/services/features.html tells customers how to hang up and dial *64 (Touchtone) or 1164 (Rotary/Pulse) to activate CAMCT. "Listen for message. Note the date and time of the call traced. Call your local law enforcement agency to file a police report and secure a crime report number. Contact the Rochester Telephone Annoyance Call Bureau at 777-5749. Once we have identified a pattern, we will forward the information to your local law enforcement agency." This hundred year old phone company does not seem to be very big, but it has every conceivable service, including ISDN and dial-up Internet.

• http://www.infobahnos.com/~ benh/text/cidlegal.htm is a Pennsylvania Public Utilities Commission judgement on Caller ID from 1990, which quotes a US $1.00 activation fee for CAMCT.

• Cincinatti Bell, in http://www.cinbelltel.com/text /faq/index.html states that CAMCT is available for a US $6.50 once-off start-up fee, no monthly fee and an activation fee of "$5.00 in Kentucky and $1.50 in Ohio and Indiana." http://w ww.cinbelltel.com/text/residential/general/responsibility.html has further details.

• Nynex, a New York / New England US telco, in http://www.nynex.com/pr oducts/b_call_trace.html states: "Call Trace is an effective way of combatting annoying, threatening and harrassing phone calls. Using the switching power of the NYNEX network, you can accomplish on your own what used to require complicated intervention. Call Trace will trace a bothersome call, record your number and the number of the caller, then forward the information to the Annoyance Call Bureau. . . . Your phone is already equipped for Call Trace, and there's no charge for the connection." However it only works for calls in the local area. No such problem would be encountered with CAMCT in Australia - calls from anywhere in Australia, including mobiles, would be traceable, since the carriers all use CCS7 communications between their modern exchanges and pass the caller's number between themselves. "To Activate: Touch-tone: Hang up, lift receiver and press *57. Rotary: Hang up, lift receiver and dial 1157. To initiate an investigation, call the Annoyance Call Bureau (listed in your local directory) and your local law enforcement agency. You'll be charged $1.50 for each successful trace."

• Southwestern Bell, in http://www.sbc.com/swb ell/314/single_female.html describes CAMCT with a US $8 per activation charge and a US $7.75 setup fee - in area code 314. There are no monthly charges. "Call Trace is the easy way to put a stop to those harassing or obscene calls. Call Trace initiates an immediate trace of the last call you received. The number from which the threatening or obscene calls are made will be provided only to Southwestern Bell Telephone security personnel and appropriate law enforcement agencies should you pursue an investigation." http://www.sbc.com/swbell/kc/e asyopt.html gives alternative prices in other area codes: $10 per use and a $1 monthly fee in 913 and 316, and $8 per use and no monthly fee in 816 and 417. I presume this is due to differing regulations from the relevant Public Utilities Commissions. This page has an extensive table of prices for many services.

• Canadian telco AGT in http://www.agt.net/agt1/ smtouch.html#RTFToC11 describes its CAMCT service, which has no startup fee nor any need to enable the service: "AGT Call Trace service is available to any customer at any time. It costs $3.00 per traced call." "AGT Call Trace service puts an end to threatening or harassing calls. It initiates an immediate trace of the last call you received." Customers dial *57 (or 1157) and if the trace is successful, "you will be instructed to call the police to pursue further action. Traced numbers will only be released to the police."

• Bell Canada, in http://www.b ell.ca/bell/eng/products/res/smart/guide/tablee.htm provides a table of the numbers for its various services, including *57 for CAMCT. (See http://www.ati.com/aaron/text/st arcode.txt for another list.) http://www.be ll.ca/bell/eng/products/res/smart/guide/trace.htm provides the instructions and notes the court admissibility of the evidence. (CND evidence is not likely to be so easily admitted in court - especially in Australia where the customer equipment will respond to Mode 4 and so can have any message sent to it by the other party to a call.) http://www.bell.ca/bell /eng/products/info/privacy.htm states that the fee is CA $5 per activation or CA $10 per month maximum and that it is made available to all customers where is technically possible.
  (As an aside, they also offer an extraordinary reverse directory service via telephone, http://www.bell.ca/ bell/eng/products/res/smart/trace.htm in which for 50 cents, "almost any number in Ontario or Quebec" will be converted into a name and a locality - but not street address. Given the lengths to which Telstra has gone to stop the pernicious practice of making reverse phone directories available on-line, by phone or by CD- ROM, I find it extraordinary that a phone company would do it themselves. There are a number of restrictions: it does not work for numbers which are ex-directory or for which Caller ID number display has been disallowed. http://www.bell.ca /bell/eng/products/res/smart/guide/match.htm )

• MTT in Nova Scotia state in http://www.mtt.ca/cmsnet2.html#tra ce that they provide Call Trace for free - but it is not clear whether this is CAMCT or a more cumbersome arrangement.

• A rural telco in South Carolina provides Call Trace (no details of what approach) for US $4 a month: http://www.lowco untry.com/lowcountry/ptelco.html#SSF "Trace harassing or life threatening telephone calls on demand. We release traced information to appropriate law enforcement officials. You must file a complaint with the proper authorities and fill out a Complaint Form at our offices. This feature works with calls within our service area."

• Another small telco in South Carolina provides "Customer Originated Trace - $3.50 / month. Trace harassing or life threatening telephone calls on demand. We release traced information to appropriate law enforcement officials. You must file a complaint with the proper authorities and fill out a Call Trace Request Form at our offices.": http://www.hargray.com/hargr ay/htelco.html This seems pretty good, but in addition to selling people's personal information (their phone numbers as callers) by offering Caller ID, like most other US telcos, they have the gall to charge $2 a month for a "blocking" option for Caller ID. In other words, they give their customers three choices: Have their numbers sold to the people they call, dial a "blocking" code before each number to stop this, or pay $24 a year! This is the sort of behaviour by telcos - like selling discs of subscriber numbers ready for telemarketers and direct mail - which make me wonder what their commitment to their customers is. It is like a hotel making money from sales people who knock on the door of the paying guests - and then offering for a fee to the guests additional protection to keep the sales people at bay!

• A Nebraskan telco offers CAMCT for $1 per activation: http://www.doc.state.ne .us/das_doc/doc/sept95.htm

• North Pittsburg Telephone, in http://www.nptc.com/costs.html states that it offers CAMCT for US $1 per activation.

• Saskatchewan 580k line telco Sasktel in http://www.sasktel.com/st4148.html offer CAMCT without charge and apparently without the need for prior arrangement. I don't necessarily think this is a good idea. Firstly, some prior arrangement should probably be made so that customers have some way of stopping misuse of the service by someone in their home. Secondly I think a small to moderate fee per activation is a good means of deterring frivolous use - however I have no information on how much a problem that would be.

• Sprint-Centel in Florida: http://www.cntfl.com/co nsumer/phone/calling.html offer CAMCT but do not give pricing details.

• The Perry Spencer Rural Telephone Company of Illinios: http://www.psci.net/psrtc/telecom.ht ml provides CAMCT (they call it "Customer Originated Trace") for US $3 per activation.

• Brookings Telephone of South Dakota: http://serv.brookings.net/callid.html provides it for US $4.

• 25,000 line APUA Telephones in the Antigua & Barbuda in the West Indies http://www.candw.ag/com/apu a/apuatel.html provide Customer Activated Malicious Call Trace.

• The Berkshire Telephone Corporation of New York provides CAMCT for US $1 per activation: http://www.berk.com/berk/ optional.html#special No prior arrangements are needed. It works for calls originating in their area or surrounding areas. More details at: http://www.berk.com/berk/ newlet.html#nuisance

• A document at http://www.ai.org/iurc/act ion/engine/960621.html , from the Indiana Utility Regulatory Commission relates to a US telco called the Geetingsville Telephone Company at what looks like a $2 per month charge for any month in which Customer Originated Malicious Call Trace is activated - apparently irrespective of the number of activations.

• The US West CAMCT service is described in http://www.puc.state.co.us/f yi/t8.html#calltrace as requiring no setup procedure, and costing $1 per activation.

• Canadian telco NewTel in offers CAMCT for CA $5 per activation with a limit of CA $10 per month: http://enterprise.ne wcomm.net/ntc/images/smartouc.htm "Use Call Trace to protect you and your family against obscene, harassing or threatening calls 24 hours a day, 7 days a week. Call Trace is already on your phone as part of your basic telephone service, so there’s no monthly subscription fee. If you receive an upsetting call - hang up. Then immediately pick up the receiver again. After you hear the dial tone, press *57 on a TouchTone® phone or 1157 on a rotary phone. A recorded voice message will confirm that the call has been traced. To take legal action against the caller, contact your local police department. But remember, Call Trace should only be used in serious circumstances."

• Australia's major carrier Telstra is justifiably proud of its efforts in connecting customers in this vast country, but what about Canadian telco Northwestel, who serves 100,000 customers spread over 4 million square kilometres. In http://www .yukonweb.wis.net/business/nwtel/calling.htmld/#trace they offer Customer Activated Malicious Call Trace for between CA $3.50 and $5.95 a month. If this 565 employee company can provide CAMCT, then why not Australia's telcos?

• Minnesota telco Crosslake Communications: http://www.crosslake.net/ ~crosslak/telephon.html provide CAMCT without prior set-up. Their page mentions prices for other services, but not for CAMCT.

• Muenster Telephone Corporation of Texas: http://host.ld.cent uryinter.net/nortexinfo/mtc/services.html provides Customer Activated Malicious Call Trace for US $10.00 per successful trace activation with a maximum charge of $25.00 in any one month. Like most of these CAMCT services, there is a voice message to confirm that the customer wants to proceed with the trace, and to confirm that it has been successful.

• A telco in Edmonton: http://www.westedmal l.com/tenant/edtel/callfeat.html offers CAMCT for CA $3 per activation.

• The Logan Telephone Cooperative of Ohio, in http://logantele.com/mre- info.htm#cot offers "Customer Originated Trace - Lets you trace harassing calls and if you wish, to prosecute the caller. Residential - $2.50/month Business - $3.75/month ($7.50 each police report)". Quite what this means I am not sure.

• The University of Alabama at Birmingham, in http://uabcomm.comm.uab.edu/a nnoy.htm gives details of traditional tracing arrangements, with written requests following a malicious call. This is not CAMCT and would be useless for deterring or detecting malicious callers who made one call, or a series of calls within a day or so.

• The University of Okalahoma Department of Public Safety has a guide to various kinds of unwanted phone call, and information about a limited call trace facility: http://www.ou.edu/oupd/crankpho. htm

• Telecommunications Services of Trinidad and Tobago offer CAMCT: http://www.tstt.net.tt/resid.htm There is no mention of costs. "This service allows you to trace the last call you received by entering the *57. To trace a call, you must replace the handset and get dialtone immediately after receiving the call and enter *57. An announcement will inform you whether the trace was successful or not. Traces are made on a per- call basis so, you will have to go through the process whenever you wish to trace calls. Information on traced calls will be recorded by TSTT and provided to the appropriate authorities."

• Here are some more links to telcos offering CAMCT which I found by searching for "Customer Originated Trace" with the AltaVista Advanced Search http://altavista.dig ital.com/cgi-bin/query?pg=aq& what=web and MetaCrawler http://metacrawler.cs.washington. edu:8080/ :
• Mount Horeb Telephone Co. Wisconsin US http://www.mhtc.net/callsrvs.html ;
• Silver Star in Wyoming http://www.silverstar.com/sstser v.html ;
• Heart of Iowa Telephone Cooperative http://www .netins.net/showcase/heartiowa/background.html ;
• Farmer's Mutual Telephone Cooperative of Idaho: http://www.fmtc.com/cstorgtr.htm ;
• Consolidated Telephone Cooperative of North Dakota http://ctc.ctctel.com/ctc/news_ march.htm ;
• Bruce Municipal Telephone Service in Canada http://www.bmts.com/smart.htm The Ontario Provincial Police notice regarding their $5 per activation service is at http://www.laser- imprints.com/opp/phone.html ;
• Sunman Telephone Corporation (a 98 year old company in Indiana) http://www.seidata.com/~stc/p hone.html ;
• Riviera Telephone Company in Texas http://www.rivnet.com/rates.html has a $10 per activation fee ;
• Baraga Telepone Company in Michigan http://www.up.net/upnet/b artelco/class.html ;
• The West Side Telephone Company in West Virginia http://www.westco.net/rates.htm charges $2.50 per activation for residential customers and $3.50 for business customers;
• The Northern Arkansas Telephone Company http://natco.southshore.com/class. htm

Miscellaneous links

• "Call Trace" is a general term for both traditional malicious call tracing and customer activated approach. To find a few hundred WWW references to this, go to Alta Vista's Advanced Search page: http://altavista.digital.c om/cgi-bin/query?pg=aq& what=web and search for "Call Trace" - be sure to use the double quotes so it looks for the phrase rather than occurrences of either word. You can achieve the same thing, but clicking on the following link, which has the "Call Trace" search string built into it: http://altavista.digital.com/cgi- bin/query?pg=aq& what=web& fmt=.& q=%22Call+trace%22& r=& d0=& d1= "Customer Originated" is another good search term.

• A 1990 document from telecom digest (Usenet newsgroup comp.dcom.telecom) at http://www.dimensio nal.com/~jericho/www/ess11.htm lists Customer Originated Trace as one of the Revenue Generating CLASS features developed by AT& T:

CALL TRACE     Call Trace allows the called party to
               initialize an automatic trace of the last
               incoming call received.  When the customer
               activates a trace, a message containing 
               the following information is output to the
               SCC Maintenance Channel:

               1.   Time the trace was activated
               2.   DN of the calling party
               3.   MLHG/multiline indicator
               4.   DN and LEN of the customer 
                    requesting the trace
               5.   Date and time of the TTY message
               6.   Date and time the call being 
                    traced was received
               7.   Privacy Indicator
               8.   CWT Indicator

               Activation Code:  *57
               No Deactivation Code required

These details and terminology are for the AT& T 1A ESS exchange, which is not used in Australia.

• Human interface standards: ht tp://www.ameritech.com:1080/news/testtown/library/standard/pbix4.html is an interesting set of standards for human interface design of touchtone and rotary dial telephones.

• http://arr ow.cso.uiuc.edu/telecom/feature-codes/featurecodes.html lists *xx codes for various exchange features.

• Bell South, in htt p://www.bell.bellsouth.com/products-services/call-trace-tech-desc.html promises a technical description of Call Trace - but it isn't complete yet. This directory has descriptions and prices of dozens of other services well beyond POTS and ISDN and including Frame Relay.

• Matav Rt. in Hungary have what they call a Malicious Call Trace service: http://www.matav.hu/Se rvice/digifon_e.html#rossz but it seems at odds with the usual approach. Firstly they give the number to the victim - no mention of giving it to the Police - and secondly the caller can make the call in such as way as to inhibit this function. Weird.

ISDN related links

ISDN stands for "Integrated Services Digital Network". ISDN refers to several things: specific, internationally standardised ways of bringing telephony to the home or office digitally, the protocols with which the customer equipment interacts with the telephone exchange and the network, and the way the exchanges communicate digitally - firstly for the call data and secondly for setting, managing and terminating calls with the CCS7 inter-exchange protocol. There are two major means of connecting ISDN services to customers. Firstly, primary rate ISDN (usually on a pair of fibres, but can be on two twisted pairs) - 30 x 64 k bit/sec B bearer channels and one 64 k bit/sec D channel for control information. Secondly, Basic Rate ISDN over a single twisted pair. This carries two 64 k bit/sec B bearer channels and one 16 k bit/sec D channel for control. Each B bearer can handle a normal voice call or a data call - with data being directly transferred from one customer's equipment, to the exchange, through the network to another exchange and to another customer's equipment.

The most important thing about ISDN, from the point of view of malicious calls, is that the telephone (or computer interface or whatever) is able to communicate with the exchange at any time over the D channel - including while the call is in progress. This enables an ISDN phone or PABX to alert the network of a malicious call while the call is in progress. The technical standards for how ISDN Customer Equipment does this are evolving and not currently mandatory in Europe. There is more to this than what I have available here - please email me if you are interested in ISDN Malicious Call Trace customer equipment standards.

There are reasons why this "Malicious Call Trace" during the call is not just a better way of doing it - compared to hanging up and dialling a special number. It is in fact the only practical way of doing it. With an ISDN PABX, which may have 30 calls coming into it on one PR-ISDN line, a PABX customer who hangs up and then dials an MCT number makes it hard or impossible for the exchange and the PABX to figure out which of the 30 channels the call came in on. Secondly, that channel is quite likely to have another call on it now - or even a subsequent call - making it very difficult to be sure which call the victim is trying to have traced. These issues are also a problem with an analogue connected PABX.

With Basic Rate ISDN, which only has two D channels, these problems may be lessened, however the outgoing call from a phone (one of many phones and other devices which may be connected to the NT-1 interface box at the customer's site) will not necessarily make a call to the exchange on the D channel on which it most recently received a call. In addition, the exchange can have up to ten numbers associated with a single BR-ISDN service, each of which can be associated with a particular phone (or other device) at the customer's site.

However the solution to these problems - specific protocols for the customer equipment to tell the exchange of a malicious call in progress - are greatly superior to the analogue phone arrangement of hanging up and dialling a special number.

• Telstra's lists malicious call trace as being available with its ISDN service: http://www.telstra.co m.au/prod-ser/isdn/isdncomp.htm

• A technical link for ISDN: http://www.itu.ch/itu doc/itu-t/rec/i/i251-7_23157.html is where you can purchase (for 20 Swiss francs) an electronic copy of the ITU Recommendation I.251.7 (08/92) - Malicious call identification. http://www.itu.ch/itudoc/itu- t/rec/i.html lists dozens of other ISDN standards.

• http://www.ispo.ce c.be/infosoc/legreg/docs/92383eec.html is the 5 June 1992 European Council recommendation for ISDN, which leaves "malicious call identification" as an optional extra - rather than a standard part of ISDN services and customer equipment.

• The Swedish telco Telia has what looks like a magnificent English language (and not standards-speak English) guide to ISDN protocols and services http://www.telia.se/isdnweb/engis dn.html . The section which explains Malicious Call Identification (Trace) is: http://www.telia.se/isdnwe b/circuit2.html#5.3.18

• ETSI's vote 71 of 17 February 1995 includes something to do with malicious call identification: http ://www.etsi.fr/dir/infocentre/press/press-95/vote71-1.htm#300356-11 . The index file for this is http://www.etsi.fr/dir/i nfocentre/press/press-95/vote71.htm

• Some detailed technical material from Telehallintokeskus in Finland on the "keypad protocol" for ISDN signalling between the customer equipment and the exchange is at http://www.thk.fi/tele/suomi/gfi93 03.htm "GFI 9303 19.5.1994 GUIDELINES FOR IMPLEMENTATION ISDN SUPPLEMENTARY SERVICES KEYPAD PROTOCOL" I have not checked this out in detail - it may not be totally up-to- date.

• Telenex Corporation provides a quick guide to the huge topic of SS7 signalling - the packet switched inter-exchange protocol which is the lifeblood of modern telephone networks. http://www.gsnetworks.com/ezvu/ezvu500/TUTORIAL/PROTOCOL/genSS 7.txt

• Nortel's DMS 100 exchanges can support a feature called "Malicious Call Hold" http:/ /www.nortel.com/pcnprods/mdc/library/voice/features/F1835.html which is activated during a a malicious call and will hold the line it came from. http://www.nortel.com/home/sear ch/search.html enables searches of an extensive range of Nortel exchange documentation.

Updates sorted by date

• 1996 December 17 /mct/index.html created. The first two mail-outs, on the UK and US situations are at camct1.htm and camct2.htm. cnd_mct.htm leads to a Word file which contains a table showing the many differences between Calling Number Display and Customer Activated Malicious Call Trace.
  
  
• 2005 October 19.  Placed at http://www.firstpr.com.au/issues/mct/ - but not really updated, so many links will be dead.