Main Forum >> Geographical Numbers Chat >> Nuisance calls – With CLIs of unconnected victims?

Message started by Dave on Jul 29th, 2018 at 2:00am

Title: Nuisance calls – With CLIs of unconnected victims?
Post by Dave on Jul 29th, 2018 at 2:00am
What are the current trends in nuisance calls?

Judging by calls received on a line at my property, nuisance calls tend to come with a CLI, rather than being ‘withheld’. We, of course, knew that with people blocking, or simply not answering anonymous or ‘withheld’ calls, that nuisance callers – notably those intent on malevolence, such as scammers purporting to be from Microsoft – would just present false CLIs.

While one or two calls show as International along with an international number or without any number, there is growing trend for International calls accompanied by a UK national number. Such numbers are presented in national format, as in 01234567… rather than 00441234567…. In some cases these are quite obviously false as there aren’t enough digits or it’s on a prefix that doesn’t exist.

It is important to stress that not all CLIs with a UK number are International. In fact, over the last month the number 01282 6236xx was presented a couple of days apart, one coming through as International and the other not. I have obfuscated the last two digits, but in both cases it was the same number.

The prefix 01282 623 is a Virgin Media one. Now, without wishing to sound outrageous, I doubt that ‘Microsoft’ computer fraudsters rent out a house in the UK in order that they may have a landline installed, so as to obtain use of a valid UK geographic number.

Another International call received within the last month had a geographic number presented, perhaps coincidently, on a prefix used by the same BT exchange. Various sites that list numbers and allow users to submit comments suggest it is associated with the ‘Microsoft’ scammers. Should I be concerned that they may be next door or down the street?

This begs the question, are there are growing numbers of victims whose telephone numbers have been used and therefore get bombarded by people ‘returning’ calls to them? Some of those people ‘calling them back’ will be doing so having missed the original call, and others will have taken the call, hopefully deduced it was a scammer, and thought they were ringing the scammer back.

There are services such as BT Call Protect, which collects nuisance-call numbers so as to block calls ‘from’ them. Does this mean that these victims get hit twice? Firstly, from people calling them back, so to speak, and secondly, by finding that some of their outgoing calls are now blocked (as the people they are calling are using a blocker that now has them blacklisted)?

Title: Re: Nuisance calls – With CLIs of unconnected victims?
Post by Ian01 on Jul 29th, 2018 at 8:08am

Blocking based solely on CLI is a fools errand. It is ineffective (as the scammer will likely present a different CLI next time they call) and, as you note, is filling your block list up with phone numbers that belong to genuine non-scammer people and businesses or are numbers that don't exist (either a number that could exist, from a genuine area code, but is currently not in use, or a number with a prefix that hasn't been allocated yet or a number with an incorrect number of digits such that it could never be valid, irrespective of the prefix).

There are a number of "who called me" websites online and they are filling up with comments about a huge number of numbers including obviously unallocated prefixes and malformed numbers but also including numbers that do actually belong to genuine non-scammer people and businesses. This could harm the reputation of those people and businesses.

It is call-blockers based on trueCall that are effective, challenging unrecognised callers to speak their name and the called telephone handset rings only if the caller completes the challenge. This system is available as a plug-in box, built in to BT "Call Guardian" handsets such as the BT8500, BT8600 and BT Halo series, and latterly built directly into some telephone networks such as Sky (Sky Protect) and TalkTalk (Talk Safe).

BT Call Protect has issues and raises a number of serious concerns about its functionality and effectiveness as well as the danger that genuine people and businesses may be being blocked from making calls to BT customers after scammers from afar spoofed their telephone number and presented it as if it were their own.

Title: Re: Nuisance calls – With CLIs of unconnected victims?
Post by Dave on Jul 29th, 2018 at 5:47pm
It is, indeed, a game of cat-and-mouse. So where are we at?

The possibilities in respect of presenting junk CLIs have been reduced, with some degree of validation, I believe. From what I can see, through my experience, it looks like the nuisance callers now are moving to make calls in a way that presents a possibly-valid UK national CLI, and with the call not appearing as International (some do while others don’t). That is, no longer do we have CLIs consisting of several zeros or several other digits.

If the BT Call Protect block list is indeed a list of numbers that have been presented by nuisance callers then it can go on forever adding numbers until no one can call anyone who uses the service. The nuisance callers, experiencing their calls being blocked, will move to pastures new in the form of different numbers, with the only calls to be blocked being genuine ones from the rightful user of the number. Eventually, nuisance callers could get to a point where, in order to circumvent blocking, they need a random-number generator so as to offer a totally different CLI for each successive outgoing call.

What the BT Call Protect service does offer is a good marketing opportunity. BT can say how many numbers are on its block list – hundreds, thousands, tens of thousands – in order to sell the product. If a competing provider offers a similar block list, then they can battle as to whose is biggest. With that, there’s no reason to remove numbers from the block list and every reason to keep accumulating them!

With today’s technology, would it be possible to change CLI so as to provide authentication, I wonder? Obviously, there would have to be international agreement and telecommunications companies in different countries would have to make changes to their systems. Could part of the solution include passing the number the caller dialled to the called party, allowing organisations to verify that the customer called the official number, and not some third-party revenue-generating ICSS number?

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