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Foiling 'Backdoor' Voicemail Spam? 53

Cheffo Jeffo asks: "After receiving a number of (repeated and irritating) voicemail spams in the past week, I starting investigating what my options were for blocking these pre-recorded messages that are eating up my mailbox and costing me money when I check my messages using a cellphone. While it appears that I can do nothing at this point in time (I am Canadian and the CRTC hasn't had the wisdom to make this stupidity illegal yet), I was wondering if there is a technical measure that I can use to stop the insanity (other than reverting to a regular answering machine). In my particular case, the telemousketeer autodialer dials into the telco's voicemail backdoor (xxx-210-0yyy) and punches in the phone number xxx-yyy-zzzz. If they find that there is no mailbox, then they hang up and remove the number from the call list. Otherwise, they leave their obnoxious solicitation.How do they determine whether a mailbox exists (as you can tell, I am no expert)?" Might there be some tone that you can record at the start of the outgoing message that will fool the autodialer into marking the number as "disconnected"?

"If I were to record the 'I'm sorry, <some-phony-number> is not a valid mailbox, please try again' message as my mailbox identifier, would that work?

Any other ideas (other than the providing Slashdot with the URLs for the offending companies to punish their web servers)?"

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Foiling 'Backdoor' Voicemail Spam?

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  • 1) First Post
    2) The standard Tri-Tone OOS tone might help, otherwise. I think the CRTC is your best bet.
  • by egerlach ( 193811 ) on Tuesday September 30, 2003 @12:58AM (#7091514)
    My girlfriend did just that when the voicemail spam got out of hand. Their message now says "If you are going to leave an advertisement of any kind, hang up now because we will not respond. However if you are trying to reach..." and so on.

    They haven't a single ad since.
    • Taking that a step further: one popular anti-telemarketing startegy is to inform people that you're going to charge them a fee for dealing with their phone calls. Once they've been informed of this, they legally incur a financial obligation every time they call. This should be legally valid in Candada too.
      • Informing telemarketers and spammers that you're going to "charge them a fee" for dealing with their phone calls or spam is the most rediculous suggestion I've ever heard. Who on earth actually thinks this works, aside from FM6? And thanks for the expert opinion on the legal system in Canada. I had a similar problem with harassing voicemail messages. Someone must have busted into Bell Canada's system, because despite the 3 minute maximum, I was receiving 48 minute "radio shows" of rap music interpersed wit
        • You need to cut back on the caffeine. At least I hope it's caffeine...

          I stole the fee idea from Private Citizen []. I first heard about them some years ago, when their founder got interviewed on NPR. At the time, he was just distributing information on how to sue telemarketers in Small Claims Court. (He described the attitude of his first trial judge to the defendent: "Last evening I had my dinner interrupted three times. You lose buddy.") Now I see that they offer a subscription where they publish your name

    • FWIW -- I recorded the message that you get when you use the backdoor and enter an invalid mailbox number (I used a mailbox that differed from mine only in the last digit) and used that as my mailbox identifier (the announcement that you get when you use the backdoor and enter my mailbox number).

      It's been 24 hours and no voicemail spam as yet ...

    • The problem is, most of the voice spam I get on my answering machine is pre-recorded. I get the feeling it's some new telemarketer strategy. They call you, if their autodialer detects an answering machine they just leave their prerecorded crap, if they get a real live person then they switch you to a human telemarketer to make their pitch.

  • You're hosed. Once they've got your number as a live person, you really have no recourse.
  • But since I have not lived in Canada long enough and recent enough to say any word about how their telephone spammers works, but in the US, people who use telezapper thang-a-magic, swear by it, telling that it reduced 90% of their telemarketing calls. Me ? I am a die-hard freebie fan, use a regular answering machine to screen calls and erase them when I get an ocassional one or two every week.
    • How would you plug that into a cell phone?
    • The problem (for me) is that the telezapper only defends against calls received ... these bastards punch straight through to voicemail ... my phone never rings.

      But, to be fair, my parents (who live in the US) swear by their telezapper ...
    • All you have to do is get your phone number listed under the maiden name of yourself (if you're female and married) or the maiden name of your wife/mother as appropriate. Then whenever anyone calls for that name you know it's a phone spam and you can legitimately tell them there's nobody there by that name and hang up.
      • Doesn't work for the automated voicemail thing the OP is talking about.

        Of course, when it's a human, if there's ANY hesitation in the "may I speak with...." then I just hang up immediately. So far I haven't gotten any false positives (that I know of, and if I have, apparantly they haven't been very important ones)

        btw, I thought I'd read somewhere that (in CA anyway) it was illegal to leave automated messages. I'd say I get more calls that are recorded messages than I do actual people (reaching both my v
  • Ask Woz (Score:3, Funny)

    by JonoPlop ( 626887 ) <me@Jonatho[ ] ['nMa' in gap]> on Tuesday September 30, 2003 @01:52AM (#7091666) Homepage
    I wonder if Steve Wozniak [] has been keeping up with the phone system like he used to. P)
  • Suggestions... (Score:4, Interesting)

    by sbryant ( 93075 ) on Tuesday September 30, 2003 @01:55AM (#7091674)

    Do the spam messages occur at regular intervals? You could try turning your voice mail box off for an hour/day/week. The idea being that they call, find no box, and delete your number from the list.

    Starting the message with a "disconnected" tone or somesuch might help. This might not work though - if they're using a computer with ISDN technology, the card gets told digitally when the call is disconnected (or rerouted etc).

    Have you registered a complaint with your telephone company (mobile provider or whatever)? Even if they refuse to do something, make sure they get a complaint - written is usually best. If enough customers complain about something they will look into it. Find out if their competitors are willing to help, and if they are mention it in your letter. The prospect of losing a customer to a competitor will carry more weight!

    -- Steve

    • The telco is on-board and is currently involved in legal actions against a couple of these operations.

      The problem that they are running into is that the CRTC hasn't decided if existing telemarketing rules (e.g. no prerecorded or synthesized messages may be used for any type of solicitation) apply to direct-to-voicemail spam.

      The spammers argue that, since the phone never rings, the rules don't apply.
  • complain / sue (Score:3, Interesting)

    by complete loony ( 663508 ) <Jeremy,Lakeman&gmail,com> on Tuesday September 30, 2003 @02:14AM (#7091738)
    1) The telco is providing this dubious backdoor service
    2) The service is costing you money
    3) complain to the telco, threaten to swap services (if you can)
    Note, in australia I would complain to the TIO, as this costs the telco money either way.
    4) ???
    5) PROFIT
    • Do you have provincial regulatory commissions in Canada? If the telephone company is not being cooperative, try filing a formal complaint with your provincial (state in the US) regulatory commission. Utility companies hate formal complaints. They have to respond to the regulatory commission and the whole thing is on the public record.
  • by Anonymous Coward on Tuesday September 30, 2003 @02:17AM (#7091745)
    Spammers assume that if you don't like their message, you'll simply delete it. Only a tiny fraction of recipients ever actually respond, and most of those responses are for placing orders. This means they can employ a very small number of customer service reps, making spam very cost-effective. The reason it works is that you, the victim, simply delete the spam and take no action.

    To force spammers into finding a better way to conduct business, we must tip the balance of costs. If every victim called them up and wasted 5 minutes of the spammer's time, the ratio of sales to non-sales would become pretty thin, pretty quick. Their costs for paying phone-monkeys would quickly surpass penis pill profits.

    It's even better if they have a toll free number you can call, because it's their dime. (Beware of ANI, don't counterharass them from your own phone!) It actually costs them extra if you call them from a payphone, hint hint. I got answering-machine-spammed a while ago, and it turns out that 800 470 0865 is also answered by a machine. There's a voicemail system behind it, and it's possible to tie up the line indefinitely just by pushing 1(wait)*(wait)1(wait)*(wait)....

    If they have a website you can visit, well, I'm sure you can figure out what to do. Evil blackhats of the world, unite and make the world a better place! If spammers' hosting costs skyrocket, they might see the light.

    Place an order! Then cancel it. Document both. Keep CLOSE TRACK of your CC bills! If they charge you anyway, reverse the charges. (That costs them BIG, and if it happens too often, they'll get their merchant account canceled.)

    It only takes a small percentage of spam victims, pissed off and ready to take action, to impact the spammers' bottom lines. You probably spend at least 5 minutes a day sorting through spam email, listening to junk voicemail, and throwing out the dead-tree junk that lands in your mailbox. Spend 5 minutes a day fighting back.
    • Certainly, something needs to be done ... one of the arguments that telemarketers/spammers make is that such a low percentage of people request removal, that there isn't a problem.

      I did tie up the receptionist and owner of the firewood delivery firm (the spam was sent on their behalf) for about an hour, demanding the name, address and phone number of the spammer (which I think I am entitled to under current legislation).

      I requested callbacks, then didn't answer ... then called back again ...

      Perhaps no
    • What we need is a cheap, disposable device which is small enough to be taped to the microphone end of a payphone headset, which will play back a predetermined series of DTMF tones in an infinite loop, such as 1, *, 1, *, ...
      • Define cheap.

        You can get a basic stamp cpu for anywhere between $30 and $60, with maybe $10 more in parts (speaker, battery, a board to put them all together on, etc) and maybe an hour learning to code its DTMF commands, and you can build one yourself.

        I dunno if close to $100 is cheap or not for ya though.
        • Get a Radio Shack tone dialer with preprogrammable sequences (up to 33). Not sure how long it'll keep playing a sequence of tones, but that'll be a hell of a lot cheaper ($25 + shipping) than your $100 creation. I'm sure you could find the source in Asia where Radio Shack gets their dialers and buy it even cheaper than that. (google is your friend)
  • Fight back. (Score:2, Redundant)

    by Associate ( 317603 )
    Try ordering whatever they're selling, then cancel the order. Then order it again and cancel the order. Then order it again and cancel the order. The idea being that you cost them more money than they would make just trying to do business with you. With any luck, they'll get the message.
  • by turg ( 19864 ) * <(turg) (at) (> on Tuesday September 30, 2003 @07:36AM (#7092897) Journal

    Check out this help wanted ad from Boxpilot [] (one of the companies in this business) to see how this is done. A live person calls your company and asks the receptionist to be transfered to your voicemail box, and then s/he presses play on the message. There's no automated/technological solution to block that, and I don't know if you want the receptionist to question the intentions of anyone who wants to be transferred to your voicemail.

    • While I have no doubt that this happens, it is specifically not the case I am experiencing ... this is a residential phone line with no receiptionist.

      They are definitely dialing into the backdoor (which is also used to check your messages from a phone other than your own) and punching in my mailbox number.
  • by sharkey ( 16670 ) on Tuesday September 30, 2003 @09:40AM (#7093891)
    to Happy Dude. You have the power!
  • Boop-boop-beep (Score:3, Informative)

    by UnrefinedLayman ( 185512 ) on Tuesday September 30, 2003 @09:51AM (#7093967)
    Yes, if you set your voice mail message to use the triple tone indicating that the number has been disconnected then it will take you off their list.

    I've gone one better and found an entire WAV of the "We're sorry" message online, and have that for my voice mail message. Now, not only do telemarketers not have me on any lists, but only the people I know and want to have call me leave me messages.

    If you'd like the WAV or can't find just the three tone WAV (you can have just the three tones then put in your real voice mail message; the telemarketing systems won't notice), post a reply here and I'll work out a way to get it to you.
  • Several tips: (Score:3, Insightful)

    by FFFish ( 7567 ) on Tuesday September 30, 2003 @12:43PM (#7095764) Homepage
    - I believe the CRTC would readily consider this to be equivalent to unrequested commercial faxes, in which case you have a *VERY* big club to fight with.

    - I believe the telco will readily reduce your bill by $X per month if you can provide a suitable $X for the cost of these spam messages.

    - There is a national opt-out service which is highly effective. I don't know the number off-hand. I recall having to hassle the telco to get the number, and it did take a bit of phone tag to find the person who did know it. But in the past eight years, I've had NO telemarketing calls and VERY LITTLE junk snail mail.

    - If you can identify the company that left the mail, I suggest you can take them to small claims court for the cost of retrieving their mail, the cost of filing the claim, and the cost of attending court. And I expect you will win (for starters, they won't show up to defend themselves!)

    All in all, I think you can readily resolve the problem, quite possibly to your profit!

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