Wednesday, 24 August 2016

Hello, I’m from TalkTalk….

In this blog post I’m going to be referencing TalkTalk as the telecoms provider, though in reality it could be any telecoms provider but using a known brand that has both had a known breach and customers have been subject to these scams makes it easier to put this into some context.

Several people have asked do the people behind the scam calls purporting to be from TalkTalk really have your personal data? If they asked for Johnny Rage, its likely they know something about me, however a number of recipients of these calls are just being told that its TalkTalk calling them. Even more perplexed are ex-TalkTalk customers that get calls from TalkTalk even though they’ve moved to another provider such as BT. Is this just brute force dialling of phone number ranges similar to the “I’m from Microsoft and you have a virus…” calls were now all aware or could these be more targeted? Could you determine with some accuracy the telecoms provider someone is using simply by their phone number? That appears to be exactly the case…

Ofcom are nice enough to provide details on allocations and availability of UK telephone numbers via their Ofcom Geographic Numbers page. Think of these lists in the same way that IP addresses ranges are allocated per county instead these are telephone ranges allocated by area code to specific telecoms providers. As I'm based in Worcester that has an area code of 01905 I'll use this area code as an example, one thing to remember is that 0 is seen as a prefix to the area code, so all area codes listed on the Ofcom website will make reference to 1905 instead of 01905. You can then filter these results further by the Communications Provider field and select TalkTalk Communications Limited to determine a range of phone numbers within the 01905 area code allocated for use by TalkTalk.

If I were to start dialling numbers within the below ranges, I’d likely stumble across someone that is used TalkTalk. I know people on TalkTalk and their phone numbers fall into these ranges. 

01905  312***
01905  412***
01905  780***
01905  813***
01905  863***
01905  923***
01905  936***

If you moved away from TalkTalk and ported your number over to another provider that explains why you still get the TalkTalk scam calls, as you still fall into the range used by TalkTalk. Flipping this on its head and taking an offensive approach you can now choose targets based on the telecoms provider by area code.

Your also notice that some ranges within the 01905 area code are marked as "Protected" or "Free". Those marked as the latter speak for themselves, their obviously available for future allocation, not sure what the former status means, is there anything on these ranges that would answer a call?

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