john@bovine.ati.com (John Higdon) (12/20/90)
U5434122@ucsvc.ucs.unimelb.edu.au writes: > Is it possible to use a tone-sender to dial from a > payphone in USA or Sweden or elsewhere? > If this is indeed TA's worry, how effective would such a simple fix as > disabling the handpiece microphone until answer supervision be? > [Moderator's Note: Disabling the mouth until supervision would prevent > the phone from being used to call directory enquiries or the operator; > both of whom answer unsupervised, no? PAT] Remember, we're talking COCOTs here. They GUESS at supervision, so while DA, Repair, or the Operator do not supervise, this is irrelavent to the COCOT. It hears a voice and then assumes supervision. Also, most COCOTs don't present "real" dial tone to the user, but an internally generated one. The user dials the number and the COCOT uses its internal ARS tables to redial the call, sometimes adding codes to use an AOS. The fact of the matter is, virtually all COCOTs in the US are installed on DTMF equipped lines. While it is possible to spoof most of them in manners not to be mentioned here, the straightforward use of a hand dialer is not one of them. Either the COCOT equipment is weenie, or the owners/installers are ignorant to the built in security it employs. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
U5434122@ucsvc.ucs.unimelb.edu.au (12/21/90)
As I described earlier, Telecom Australia has begun installing debit card telephones, which have fancy LCD displays and pushbutton keypads, instead of rotary dials (my, we are backward, aren't we.) I have been trying to discover why these payphones do not have DTMF dialling enabled. I accosted an installer yesterday and grilled him as much as he could take. The payphones *do* have DTMF capability (I saw the internal switch) but orders are that all are to be left on 'pulse'. I asked for a reason. First reason was that the exchange did not have DTMF enabled. I pointed out that the phone was connected to the 899 exchange which is totally computerised, and thus DTMF was available on all lines. The installer answered that it is there "at customer request, and we (TA), as the customer, don't want it." On further grilling, it appeared that TA was afraid of fraud, and so disables DTMF from all payphone lines (except those of COCOTS whose owners ask for it.) The latest COCOT, the Blue Phone, apparently has some sort of device which prevents fraud from being perpetrated whether DTMF is enabled or not. Or perhaps TA just charges the owner for all calls anyway. What TA is afraid of, I believe, is someone (lots of people) with tone senders, available from the major banks, coming along and bypassing the payphone's dialling system to place calls. What I would like to know is: How do the American and Swedish telcos avoid fraud of this type? (They are the only two countries I personally know to have DTMF payphones. Comments from elsewhere are also welcome.) Is it possible to use a tone-sender to dial from a payphone in USA or Sweden or elsewhere? If this is indeed TA's worry, how effective would such a simple fix as disabling the handpiece microphone until answer supervision be? The phones *do* listen for answer supervision: they must as they don't take your money or card-credits until the call is supervised. Help appreciated, (I shall summarise and post e-mail in the New year.) Thanks, Danny u5434122@ucsvc.ucs.unimelb.edu.au Above is IMHO. Nothing to do with Telcom Australia, or Uni. of Melbourne [Moderator's Note: Disabling the mouth until supervision would prevent the phone from being used to call directory enquiries or the operator; both of whom answer unsupervised, no? PAT]
grayt@uunet.uu.net (Tom Gray) (12/21/90)
In article <15531@accuvax.nwu.edu> U5434122@ucsvc.ucs.unimelb.edu.au writes: >As I described earlier, Telecom Australia has begun installing debit >card telephones, which have fancy LCD displays and pushbutton keypads, >instead of rotary dials (my, we are backward, aren't we.) >I have been trying to discover why these payphones do not have DTMF >dialling enabled. I accosted an installer yesterday and grilled him >[Moderator's Note: Disabling the mouth until supervision would prevent >the phone from being used to call directory enquiries or the operator; >both of whom answer unsupervised, no? PAT] Disabling the mouth piece would prevent the customer from placing an operator assisted call or conversing with an intercept operator. In any event supervision is provided to the originating office by the CAMA office. The CAMA office does this to instruct the originating office to perform the ANI spill. Only then will the customer be connected to the operator. Thus a local office has no way of knowing that the call has been completed. Operators may converse with a payphone before or after supervision is given. Operators may have to request extra payment on an existing call etc. Fraud is prevented by disablng the DTMF pad when the customer is connected to an operator. This is done by either reversing the battery to the set or by providing +48v supervision.
hpa@casbah.acns.nwu.edu (Peter Anvin) (12/23/90)
>What I would like to know is: How do the American and Swedish telcos >avoid fraud of this type? (They are the only two countries I >personally know to have DTMF payphones. Comments from elsewhere are >also welcome.) Is it possible to use a tone-sender to dial from a >payphone in USA or Sweden or elsewhere? Swedish payphones (or, in fact, any Swedish phone with the proper equipment installed) have access through the phone line to a pulse signal sent out for each marking period = 0,23 SEK. In other words, although I have not tried it myself, I presume anyone could use a tone-sender on a Swedish payphone, but it wouldn't help: you would have to feed it coins anyway! Televerket (Swedish Telecom) sells a "COCOT phone" to anyone that wants one, it is just to plug into a regular Swedish four-prong phone jack. (By the way: all the four RJ11 wires are mandatory in Sweden and are supported by the phone network: there are TWO twisted-pairlines (for a total of four wires) in the local loop to each line. Maybe that has something to do with it. Further note of interest: You have to feed a Swedish payphone its minimum fee (the payphone fee for two marking periods, usually two SEK) before it gives you dialtone (but you dial the number at the dialtone). Therefore, it costs you two SEK to call a "toll-free" 020- number from a payphone. Here in the USA, it seems like the amount of toll to pay is similarly controlled from the switching office, except for local calls, which are untimed anyway. Illinois Bell's payphones give you a digitized voice telling you how much you should put in the slot and which warns you when you are about to run out of money. Doesn't sound like something run inside the phone, IMHO. H. Peter Anvin +++ A Strange Stranger +++ N9ITP/SM4TKN +++ INTERNET: hpa@casbah.acns.nwu.edu FIDONET: 1:115/989.4 BITNET: HPA@NUACC RBBSNET: 8:970/101.4
julian%bongo.UUCP@nosc.mil (Julian Macassey) (01/03/91)
In article <15648@accuvax.nwu.edu> hpa@casbah.acns.nwu.edu (Peter Anvin) writes: X-Telecom-Digest: Volume 10, Issue 902, Message 3 of 10 >jack. (By the way: all the four RJ11 wires are mandatory in Sweden >and are supported by the phone network: there are TWO >twisted-pairlines (for a total of four wires) in the local loop to >each line. Maybe that has something to do with it. This must be something new. When I was in Sweden (1970s), there were only two wires needed. Phones given to me by Ericsson and Televerket in the 80s also only need Tip and Ring. The telephone ICs made by RIFA (Ericsson) are also two wire devices. So what is the second pair of wires used for? Any Ericsson or Tele people care to comment? Silly trivia: Swedish phones have the world's lowest minimum current spec - 12 mA. The U.S. is 20 mA although a 2500 set will usually work fine at 14 mA. Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian N6ARE@N6YN (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495