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Can BT’s call-divert service really cut off nuisance callers?

Cutting off nuisance calls

Nuisance calls are a big problem. In response, BT has a launched a new, free nuisance call-divert service. Guest author Kelly from BT Consumer explains how it works.

Many of you here on Which? Conversation will be well aware of the menace of nuisance calls and texts. Indeed, over half a million people have backed the Which? campaign to call time on them.

On average, people receive four nuisance phone calls every week, according to BT research.

The same research also shows that many people find these calls more than just annoying: two-thirds of women and just over half of men find them stressful, and more than a quarter of all people are concerned about their parents or grandparents receiving them.

Nuisance calls are most commonly from accident claims companies, but also regularly include calls from PPI companies plus computer technical support and personal data request scams.

But the big question is what can be done to reduce these calls?

Customer protection

In response to the growing problem, BT has launched its new, free Call Protect service for its customers.

The first of its kind in the UK, it could see 30m nuisance calls per week automatically diverted to a junk voicemail box, before they can be answered.

Data shows that up to 15m calls a week will be blocked from personal accident claims and PPI companies alone.

This has been made possible by technology that processes large amounts of live data to identify rogue numbers (often those calling large numbers of people) and adds them to the BT blacklist.

Personal blacklist

Although the blacklist will divert the top offending nuisance callers, for calls not captured by the technology, customers will be able to compile their own personal blacklist by adding individual unwanted numbers. They do this by dialling 1572 after receiving the call or by going online.

If large numbers of customers identify troublesome numbers they wish to divert, these will be added to the wider BT blacklist.

Customers can also set BT Call Protect to divert whole categories of calls such as unrecognised calls or those from withheld numbers. The service will then prevent these types of calls from reaching the home by diverting them into the junk voicemail.

This is a guest contribution by Kelly Barlow from BT Consumer. All views are Kelly’s own and not necessarily those shared by Which?.

Do you think BT’s call-divert service will work? If you aren’t a BT customer, would you like your phone provider to offer a similar service and what else do you think can be done to crack down on nuisance calls?


How does a call blocker stop the ones that keep changing their number every time? If you simply press the red button how does that block the next time when they change the number?

No on both counts San , do you notice the numbers usually begin with -0- thats to stop you blocking them -“en bloc ” as its the start of the area codes for the UK , you cant therefore universally block -01-02-etc as you would block genuine area code calls , as is possible on my call-blocker . The same principle is used in the USA , not stupid those “India call-centres ” .

I have been in the past in some heated discussions as to the DETECTION of an incoming SCAM/sales call . I have always said ( for years ) that it is possible for BT ( and others ) to sense where those calls come from BEFORE they are answered . I was “shouted down ” . Well guess what ? its available –but in USA exchanges via a paid for app that (as far as I know ) is not available for use on BT,s exchanges so I will post the name of it as it wont work in the UK , so I am not advertising it as its unavailable in this country . Its called Robokiller and blocks all those calls that this whole convo is complaining about -4.5 Billion robocalls were made in the USA in June -2018 . For my “unbelievers ” read on RoboKiller is the #1 solution to stop your neighbor spoofing problem
RoboKiller is the #1 app to stop the spam calls and neighbor spoofing madness. Unlike most robocall blocker apps, RoboKiller is specifically designed to valiantly fight against illegal scammers, spammers, and robocallers.

With RoboKiller, you can effectively block neighbor spoofing spam calls and take revenge on the illegal spammers responsible for the epidemic.

How does RoboKiller do this? RoboKiller uses a highly sophisticated (and also patented and award-winning) Audio Fingerprinting system to analyze the audio of every single spam call. While the numbers may be spoofed, the actual call is almost always the same. They come from a robocall or even a call center somewhere in another country.

RoboKiller uses this “fingerprint” to tell if the call is from a good guy or a bad guy – regardless of the phone number it appears to be originating from.What does that mean for you?
RoboKiller can tell you which NPA-NXX – (area code -local exchange ) calls are the ones you want and which you don’t. It’s like a sniper rifle solution instead of the sledgehammer approach.

There is nothing you need to do except sit back and know that with RoboKiller you are getting the industry’s best annoying and unwanted call protection.Neighbor spoofing is a simple process.

The spammers use a third-party call spoofing technology to call your phone while showing a phone number that appears to be from your specific area code or NPA-NXX. The spammers’ technology allows them to send a high volume of neighbor spoofed spam calls at the push of a button.

Spam callers hope they will trick you into answering because it looks like a phone number you might recognize. Often enough, it works because people would prefer to take a chance at dealing with a spammer than miss an urgent phone call. By the way my call-blocker blocks VoIP/ as well as single digit “0” type -single digit spoof calls . You can of course block area codes /national codes but thats cutting off your nose to spite your face as it blocks calls you might want. .

Duncan – thanks that’s interesting.

I found more info here:


Would I be right in thinking that robokiller is only available for smart phones and not landlines?

As of this moment – October -2018 ,yes Derek but you know and I know there is nothing stopping this new technological breakthrough ( not more than a year or so old /or less ) being implemented in landline exchanges . I have been following the constant updating of our digital network systems and ( IMO ) I cannot for the life of me see why it cant be used on our national network except for -well you know – “policy ” . Its been available to the ” 5-Eyes ” for a long time except in a different electronic software design and procedure , this is just a new modern public engaged version . Honestly Derek I cant see either BT or HMG going along with this and all sorts of excuses will burst forth —but maybe I am judging them wrong ? –time will tell.

Duncan thanks for your reply.

At risk of sounding like Ian, how do you know what I know?

If I’ve understood what I’ve seen on how Robokiller works, it is effectively using its own answer-bots to combat coll-call-bots, either to screen the calls or to harass identified cold- callers (bad news then, if you’re a false-positive).

I like that – it’s very much a “Dr Who” solution. (At least for classical Who…)

But – fundamentally – doesn’t that screening depend on the bots actually answering the calls to take a voice-print of the caller?

If so, wouldn’t deploying this at exchanges require consumers’ permission for their telephone companies to listen-in on their calls for the purpose of call screening?

Oh god Derek ! you know I don’t like some of Ian,s comments and I have made the fatal mistake of replying in kind . Dont you know I was praising you Derek –its a compliment not a “put down ” ? Anyway I realised you would bring that up as it occurred to me , as I posted their advert -verbatum their written logic in English leaves a lot to be desired . If it was After the call was answered it would be no better than an ordinary call-blocker –notice they don’t say “speech ” but Audio Frequency in other words its the calling data not the actual ringing tone generation itself inside the or along with the tones that are detected . This sort of detection has been used in radio transmission and cell-net data (signal inside a signal ) for a long time – think of FM radio where the high band frequency is modulated with the low audio frequency that’s the basic . Sorry they are keeping the actual design a secret Derek so I cant be more explicit .

Duncan – if they’ve patented the design – what does their patent actually say?

One of the problems of this digital age is that the way digital communications work is so much more difficult for the average person to visualise than straightforward mechanics. Not knowing how something works means the potential for unexpected or unwanted effects of the technology is an unknown and the average consumer feels helpless in addressing abuse of the technology. This makes it so much more important that the service providers and Government step in. Duncan, you say above that you can’t see BT or HMG going along with the American Robokiller technology: maybe I am missing something obvious but, why? Do the phone companies make money every time we pick up the phone to one of these scammers? These calls have a real impact on people’s lives even when we are not taken in by them. If the Government was to take some decisive action to require phone companies to use this blocking technology I am sure it would be very much a vote winner (and boy could they do with one at the moment!)

Expediency Beildman this has already been agreed in conjunction with the business world , not just in the UK but in the USA to expedite Globalisation -along the lines of –the public should take no heed of where the call originates only buy the product , so if it originates in the USA its still “local ” in business terms . Also many businesses are secretive they don’t want you tracing a call back to some off-shore entity or finding its a small flat in a hi-rise . Having worked for BT and talking to many people over about 19 years I found out a lot of things that were kept quiet it broadened my vision of reality . The public in this country don’t know half of what goes on now in this digital age and , believe it or not , the USA is actually more open than this country , its -don’t tell the public here . I got reprimanded to telling a business that its digital telephone system had flaws -bugs as they are called now, the CEO of the company complained and BT worked out it was me -told to keep my mouth shut. I agree with your summation Beildman but I wont be holding my breath.

Derek its done using a call-forwarding system and a digital processing computer where the call is analyzed using audio pattern breakdown to find first whether its a robocall or not then its traced back if its on a white-list the call is forwarded to the recipient otherwise its analyzed . Not so good I have just found out Google is involved ,some calls are also sent to a server for holding so that the customer can dial an access number to listen to them . This is not as sophisticated as our security services I am sorry to say.

Duncan that’s interesting, but can they really analyse the signal traffic audio without first using a bot to answer the call?

Thats why I am disappointed Derek they need the bot, our security and the USA,s dont its down to the amount of money spent on software/hardware . What I initially put forward as theory is the probable means used by our authorities , I will now see if I can find the actual digital processing used by them. I now see Google seem to at least co-own the patent , maybe own it outright .

Ah, but surely our security services will have their own omega 13 devices 😉

Your good Derek now I don’t know if you are talking SF or are just using it as a model , yes we do have our own but information is shared over all communication networks ( 5 Eyes initially ) and as always the UK gives away its technology and secrets free to the USA. . Galaxy Quest the Movie but they need beryllium I don’t have any available at present -no cant find any on Planet X -beam me up Scotty – aye captain -said with an Irish / American accent –and the star-ship Enterprise goes on its merry way to instill the American Dream to the Klingon’s and every other race in the Galaxy (leaving bases on each planet).

So that’s why there’s a delay whenever I phone Uncle Rudineer in outer Kazakhstan, or why there’s an odd echoing sound whenever I call 国家安全部 (MSS) to speak to cousin WonLung in Bejing. And I thought I was just being paranoid…

16 December 2018

Well I have had nuisance calls from one no and when I press button one to block it ..the message says no already blocked ? How can that be the calls get through ..

Eric , normal practice for those robo scam calls via VoIP is to use a block numbering system –
ie- one digit difference in the range .
Call-blockers can use all VoIP calls blocked and/or single number blocking, — without knowing the make/ model of your blocker or phone or if the blocker is built into the phone its hard to give a precise answer .
Mine does both but they all vary ,, it might genuinely be a faulty blocker but I cannot commit myself to an answer until you post the -make-model etc of your blocker.

We had the call blocking service with BT and added numbers to block the calls. Adding just 6 numbers pretty much blocked all our nuisance calls. In the finish, we blocked about 12 numbers. All was peace and quiet…
Then BT transferred us to their standard broadband tariff when our ‘deal’ was up and the monthly cost virtually doubled. So we moved to EE. And all the blocked calls came back with a vengeance! We’ve since taken on EE’s equivalent call blocking service. We’re still saving about £30/month but now in the process of building up our blocked number list again. It would be useful if the switch process could include transferring the blocked call numbers list.

Not possible Pat under the governments unbundling legislation each company has its own equipment in BT,s exchanges -different hardware/software.
BT is not allowed to interfere in any way (unless emergency ) with other ISP,s equipment and that includes EE even if it is not a subsidiary of BT.

john beach says:
8 April 2019

i have had the bt call protect for about a year, and it woks well,however the call blocked list has today become full forcing me to delete a blocked number before i could enter the new one.so i think i shall go for a cpr device instead.

Raymond Whitehouse says:
22 May 2019

BT does not provide BT Call Protect for fibre to the home/Premises (FTTH/FTTP) services so is pretty useless if you use fibre to the home. Magically though they still provide their fairly pathetic paid for services which don’t really work. Which could help here by putting pressure on BT over their FTTH facilities.