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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?

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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?

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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?

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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!)

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

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

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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 ..

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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.

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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.

We have BT “call blocker phone” which allows us to block a number if we have answered or not recognised the callers number. That is OK as far as it goes as it prevents the scammer accessing our answer phone. The one problem is it still allows them to ring, normally at 0800 ish. So you get up and block them until the next day when they change the number and you block that and so on. I’d welcome any suggestions.