Received: by bu-cs.BU.EDU (5.58/4.7) id AA03460; Sun, 29 Jan 89 00:17:31 EST Message-Id: <8901290517.AA03460@bu-cs.BU.EDU> Date: Sun, 29 Jan 89 0:02:27 EST From: The Moderator Reply-To: TELECOM@bu-cs.BU.EDU Subject: TELECOM Digest V9 #36 To: TELECOM@bu-cs.bu.edu TELECOM Digest Sun, 29 Jan 89 0:02:27 EST Volume 9 : Issue 36 Today's Topics: "Please press pound sign to disconnect your call now" Re: PINs and Calling Cards as credit cards Re: Kredit Kard Kwestions Re: Cellular Setup Re: AT&T 1300 Answering system ---------------------------------------------------------------------- Date: Sat 28 Jan 89 16:53:46-EST From: INTERMAIL@A.ISI.EDU Subject: "Please press pound sign to disconnect your call now" To: telecom@bu-cs.bu.edu From: "Robert Gutierrez / MCI ID: 367-9829" (I lost the original message about the person that used his calling card, and when using the pound, got disconnected from his call & was promped to dial another call.) ---------------------- It seems that the calling card switch that the caller was going through did not receive the signal that the call had been answered (answer supervision), and such, the switch rec'd the pound touch- tone, and disco'ed the call. Even though the terminating switch received answer supervision (which is all that matters for the billing computers), apparently the terminating switch did not pass it up the line to the calling card switch, and such the card switch still thought the call had not been answered. With calling card switches, it is critical that answer supervision be monitored closely, or you run into problems like this. (doesn't AT&T have CCS-6???, or are some AT&T switches still using in-band signalling???). We had the same problems when a lot of our calls terminated onto Feature Group-A circuts, where we had to rely on our switch to monitor the call for ringing tones and telco announcements (alert tones, then the call progress announcement), but now that we terminate onto FG-B & FG-D circuts, that problem was history. Try explaining this to an AT&T billing rep when you get your bill. I'm sure they'll take the call off your bill (it will be obvious, X amount of calls were 1 min, and the last was over 1 minute), but it is a hassle that you have to do that in the first place. ________ (Lick and place "The Usual Disclaimers" stamp here ===>|Place | |Stamp | |Here | --------- Robert Gutierrez MCI Telecommuncations Western Region Trouble Management Center Hayward, California. ------------------------------ To: comdesign!bu-cs.bu.edu!telecom@apple.com From: comdesign!ivucsb!steve@apple.com (Stevie Lemke) Subject: Re: PINs and Calling Cards as credit cards Date: 28 Jan 89 21:02:53 GMT Sorry if this has already been discussed (don't know how I could've missed it, but anyway...): Is the four digit PIN on a calling card computed from some sort of algorithm or is it randomly assigned for each phone number? It just seems strange that just about any phone anywhere can instantly tell if you dialed the correct PIN that corresponds to your calling card number. I realize computers are really fast these days and all, but I just thought it might be some sort of algorithm or something. However, that brings up the issue of what happens when someone discovers your number and you have to request a new one, so they can invalidate the old one. I've never had this happen, so I'm not sure what the procedure is. The only thing that got me thinking about this was this: I have a calling card from GTE for my home phone. I recently called AT&T to ask them for one of the magnetic (plastic) cards since my paper one doesn't work in the neat AT&T phones with card readers. I gave the AT&T employee my phone number, but not my LD PIN. She said the card that would be sent to me would have the same PIN as my GTE card. I was wondering if this was some sort of "PIN-sharing" they have worked out, or if they use this "algorithm". I guess it must be a database, but does anyone have any more positive info. on this? ----- Steve Lemke ------------------- "MS-DOS (OS/2, etc.) - just say no!" ----- Internet: steve@ivucsb.UUCP AppleLink: Lemke ----- uucp: apple!comdesign!ivucsb!steve CompuServe: 73627,570 ----- Quote: "What'd I go to college for?" "You had fun, didn't you?" ------------------------------ To: ucbvax!comp-dcom-telecom@ee.UCLA.EDU From: ucla-an!denwa!jimmy@ee.UCLA.EDU (Jim Gottlieb) Subject: Re: Kredit Kard Kwestions Date: 28 Jan 89 17:17:59 GMT In article , black%ll-micro@ll-vlsi.arpa (Jerry Glomph Black) writes: > > First, a comment on the PIN brouhaha: AT&T cards (and BOC cards) always have > had your PIN number right on the card, but as it's a 4-digit number, most I like the way New York Tel does it (I think it's the only thing I like about them). Their calling card has ONLY the PIN on it, at least in cases where the first ten digits are the same as your phone number. This makes the most sense. You already know the first ten. And if someone finds the calling card, with just the PIN it's worthless to them. > I'm a bit perplexed by the 'international' number > on the bottom: 1M,<10-digit phone no.>,<1 digit>. It seems pretty easy to > guess or 'exhaustively' determine the digit for anyone, if it only takes a > maximum of 10 tries! True. It follows a check-digit system like calling cards used to. It _is_ rather easy to figure out (given a few different cards to look at), but it can only be used from outside the US so the potential for abuse is minimized. Though I guess you _could_ hack up a similar number for the country you wanted to call to from here. > A mundane question: I have a Sprint FON card. It gives the 800-877-8000 > number to access the service, but no mention of a 950-1022 or whatever Sprint has eliminated their 950 numbers for calling card use. It is now only for those poor slobs without Equal Access. -- Jim G. E-Mail: or ^^^^^^ V-Mail: (213) 551-7702 Fax: 478-3060 The-Real-Me: 824-5454 ------------------------------ To: gatech!comp-dcom-telecom From: wa4mei!rsj@gatech.edu (Randy Jarrett WA4MEI) Subject: Re: Cellular Setup Date: 28 Jan 89 15:18:47 GMT In article boottrax@csd4.milw.wisc.edu (Perry Victor Lea) writes: >X-TELECOM-Digest: volume 9, issue 24, message 4 > >Question: How is phase shifting actually involved in communications between >the mobile unit and the switching office ? > >Question: Is it possible to access cellular setup channels and place a >fraudulent call with a ham radio? > >Thanks for your help .. > >Perry I can't be much help in answering your first question but I would like to say something about your second question. There are authorized Amateur Radio (ham) frequencies that are near to the cellular phone channels but the equipment required to access cellular telephone services are very specialized and very different from ham radio equipment. It is probably not possible for a ham to use his equipment to access the cellular services but it would be possible for anyone with the proper knowledge to make changes to cellular phone equipment and make it look (respond with the proper digital codes) like someone elses. So I guess that the bottom line is that no, it is not possible to access cellular channels and place fraudulent calls with ham radio. -- Randy Jarrett WA4MEI UUCP ...!gatech!wa4mei!rsj | US SNAIL: P.O. Box 941217 PHONE +1 404 493 9017 | Atlanta, GA 30341-0217 ------------------------------ To: comp-dcom-telecom@rutgers.edu From: gotway@inuxa.UUCP (J Gotway) Subject: Re: AT&T 1300 Answering system Date: 27 Jan 89 19:09:31 GMT > We received an AT&T 1300 answering machine for Christmas. > I am happy with the machine, but do not like how many rings > it waits until it answers (about 6). If I had saved all receipts > and boxes and stuff, and if it had been gotten at an AT&T phone > store, I could have gotten an upgrade to one that adjusts the number > of rings until it picks up. > > Anyway, is it possible through a chip or some other modification, to > modify my machine to answer on fewer rings? I realize that my warrenty > would be void, but if it is simple, I'd like to try it. The Answering System 1300 is a basic answering system with a fixed ring setting. It will answer after the 4th ring is received. This is programmed into the microprocessor software, and it cannot be bypassed or changed without coding up a new microprocessor. The only situations that might cause a report of the machine answering after more than 4 rings are: 1) The first ring in the house is really an abbreviated ring (less than 500 msec), so it is not recognized/counted by the machine. Then, the AS1300 will answer on the 5th ring rather than the 4th. 2) The customer is listening to the ringback over the telephone line, and that ringback is not synchronized with the local ringing. Over the line there might be fewer or more than 4 ringbacks, before the machine answers. 3) The customer's particular unit is defective. In this case it should be returned to the AT&T phone center or other retailer for replacement with a new unit. All of the other AT&T Answering System products have a ring select option (usually 2 or 4 rings with toll saver option). The new AT&T 1330 Answering System has a customer programmable ring select from 1-9 rings. -- Jerry Gotway AT&T Consumer Products Labs. P.O. Box 1008 Indianapolis, Indiana 46206 inuxa!gotway (317) 845-4523 or CORNET 338-4523 ------------------------------ End of TELECOM Digest *********************