Voice SPAM – the Fightback Begins

Voice SPAM is increasingly a problem, as the cost of making calls gets lower and lower in real terms.  I was interested to see that GrandCentral are taking steps to block Voice SPAM for their customers.  If you haven’t come across GrandCentral yet, they have an interesting product offering that alows you to have one telephone number from them, and have a single voicemail system and the ability to have inbound calls follow you to whatever fixed or mobile devices you are using at any moment.  They also have a lot of advanced features like color ringback (CRBT), call screening, and control via a web interface. 

We’ve talked here before about caller ID spoofing, i.e. that using various services you can lie about your source telephone number.  GrandCentral say on their blog that they know the caller’s number even if the caller ID is not displayed: I presume this means they’re using some good, old-fashioned SS7 signalling technology (rather than IP and SIP).  It will be interesting to see if a blacklisting approach works in the long term, since in the future spammers using VoIP technology to initiate SPAM will not be connected directly to today’s digital telephone networks, but instead will be using some kind of gateway to cross from VoIP to traditional networks.  Presumably once such a VoIP gateway gets blacklisted, the spammers will simply move to the next gateway with a change of IP address.


2 thoughts on “Voice SPAM – the Fightback Begins

  1. Kand


    A very different way to look at indeed.

    So, there is a different kind of ‘mobility’ for SPAMers to move to different ‘hideouts’ as they get blacklisted. That begs the question: Doesn’t blacklisting becomes harder with IPV6?


  2. Martyn Davies Post author

    I know there are IETF discussions underway about authenticated CallerID in the VoIP world. This will be a great benefit as today CallerID cannot be trusted, and so blacklisting is of doubtful value. I am guessing that whatever system they come up with for IPv4 will also work with IPv6. Personally I’m sceptical that IPv6 will come into wide use anytime soon.

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