Thursday, 27 June 2013

4 million number tarpit for junk callers

So, we have lots of numbers that are available to call and not assigned. Last time I checked it was just over 4 million numbers. This is because we have numbers in every area code, and we bought a company that had lots of numbers.

I have set these so that calls from unknown calling numbers get a nice message to bog them down. Technically I have assigned them to myself as the subscriber, temporarily, so that I can answer the calls.

I am first playing a message that explains this, then sending a DTMF "5", and a "1" for good measure to get their system to connect to an operator. It does not string them along for very long, but enough to waste their time. Bear in mind these junk calls are completely illegal - not because of TPS, but because they are automated and start with a pre-recorded announcement without prior-agreement.

An example MP3

This may seem like a bit of fun, and in some ways it is, but actually it does have  more serious side.

Firstly, it is a good test of the new VoIP platform. It allowed me to find a number of interesting quirks that needed tidying up, and hence improve the system. It allows me to test a lot of calls of varying durations. Even little things like the fact we were getting a few seconds of silence at the end of every call, which I have now fixed.

Secondly, it was very interesting in terms of psychology of callers. We have had hundreds of calls that we have captured, and apart from the junk callers which have a pretty predictable reaction, we have had a lot of wrong numbers as well.

My message starts "hello..." and a nice pause, and that makes people think they have got a person, so they say something or ask for someone. Fair enough.

Then I state very clearly that they have called the wrong number, and that we are winding up junk callers. It's a recorded message, obviously.

For a start, pretty much everyone listens to the end of the sentence, even after it is very clear they have it wrong, and could hang up straight away. Maybe they are just being polite. Many hang up at that point.

Then you get people that try talking to me again, asking for a specific person, etc. They clearly have completely ignored every word I actually said and just waited for me to stop speaking. Very odd.

You also get people who hear me rattle on, and then the beep (DTMF 5) and then proceed as if it was an answering machine message - for the person they thought they were calling. They go on to leave a message. Again, totally ignoring what I actually said.

There are the odd few that say "fuck off" as well, of course.

P.S. Why not sign my ePetition to make it easier to get compensation from junk callers.

25 comments:

  1. Can't you just connect them together and stand back and listen to all the "but I called you!" arguments?

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  2. That's quite genius. Reading that snippet of legislation, it also forbids junk faxing, not that that is much of an issue these days.

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  3. Ah but what happens when the number then gets allocated to a paying customer. It would be interested if your tarpit numbers get a higher percentage of junk calls than a number that's been totally inactive for a period of time.

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  4. Ah but what happens when the number then gets allocated to a paying customer. It would be interested if your tarpit numbers get a higher percentage of junk calls than a number that's been totally inactive for a period of time.

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    1. To be honest, I would expect not. When we last did this, with out own 1000 number block (in TPS) it was about a day before the junk callers internally blacklisted the whole block. If junk callers start realises that A&A number blocks are a bad thing to call, we will be helping all of our customers.

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  5. People don't listen to instructions...

    I have similar on my mobile phone saying "I don't listen to messages on this number, call the office on 01XXXXXXXXX where I or someone can help you"... yet people still leave messages. The majority do pay attention and call the office.

    People don't think the obvious...
    One of my numbers answers and plays nyancat on loop while recording the call - I get a lot of wrong numbers to that number for some reason. Twice I've had what appears to be hospital receptionists calling and shouting over the nyan music "HI... CAN I SPEAK TO MR. .... MR. WHITE STOP IT PLEASE, IT IS THE SURGERY" etc..
    One of the strangest calls I've had to that number was at about 5.30am on a week day someone called and after a few seconds of listening a politely spoken guy speaks to a friend or colleage near him saying "Judy.. you will like this one"... and they listen for a bit. Seems very much like a sales type call but I've never worked out why it was so early in the morning, too early for sales calls..

    Also: I love the prism addition to your recorded message ;)

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  6. Can you post a number we may call?

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    1. LOL, there are rather a lot :-)
      You have to withhold your number to get the response.
      Try 141 02000200011

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  7. Most of the junk calls to my numbers come from 08xx or geo cli. I think you are missing a lot of opportunities...

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    1. Actually we included 08xxx CLIs :-)

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  8. are you going to publish a list of CLI that fall into the honeypot?

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    1. Tsk tsk tsk. Given the callers have withheld their numbers, it would be rather naughty to publish them! Subscriber-RevK shouldn't see the numbers at all, but ITSP-RevK may receive a complaint from Subscriber-RevK and investigate... But not publish.

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    2. I don't see them - I think he means the 08xx numbers

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  9. I am wondering if now is the time to make out IVR system - see how clever we can make it, e.g. recognise the specific pre-recorded callers and have scripts specially for them - waiting for silence before saying the next pre-recorded answer, etc... Hmmm

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    1. Do it! and open source it (or sell it as a feature unlock for firebrick ;))

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    2. Or could you partner with someone like Tropo (which is open sourced at https://github.com/tropo ) or Twilio (or use something like http://plivo.com/open-source/ ) and get things running faster ;)

      Since you're sampling a large range, you could also log the billing caller id (not the CLI) in a database and once more than 3 calls to 3 different "unallocated numbers" have been logged then they are marked as a "spam caller". You could then offer an API (either restricted to Gradwell VOIP users or "public") then allows people to query "Is this a known spam caller?" with a phone number.

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    3. Why Gradwell VoIP users?

      And, at present, we are not seeing the original caller ID if withheld, sorry. Nice idea to pick up the spammers somehow. That may change in the longer term, obviously.

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    4. D'oh - sorry, I of course meant AAISP VoIP users. Stupid stupid Richy.

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    5. Is the CLI not supposed to only be withheld from the end subscriber? Telecos, such as yourselves, are supposed to be able to see the CLI - or does this only apply to calls arriving on SS7 trunks?

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    6. SS7 has it, but we don't get SS7.

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    7. It's a shame you can't get that presented to you by the upstream provider - one useful thing BT does offer is to block people by that number, withheld or not. Blocking the worst offenders on your tarpit would be a valuable addition to the service.

      Additionally, if it's legal, an enhanced anonymous call rejection which would allow the caller to opt to have their number released by pressing 7 at the prompt would help; I recall at least two callers being baffled by BT's ACR message, somehow.

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    8. I suspect we will eventually but we have to be very careful with how we use that data, obviously.

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    9. The key to release CLI is interesting - TBH I have no idea on legality. If we got raw CLI it would be technically possible. Nice idea,

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    10. It's something we offer our customers. We make it absolutely clear that we, as their telco, are offering the caller the chance to release their number and if they choose not, the end user will not be passed this information.

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  10. How about linking this up to a twitter account, so every time there's a new call, it posts the mp3 for our listening pleasure?

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