Updated 23 July 2005

These pages offer some of what I know about Silent Telephone Calls.

A separate page covers nuisance telephone calls and enforcement more generally.


In the absence of an index or glossary you may wish to search (Ctrl-F) for words or phrases (e.g. Informative Message, NAA, BT, DMA) in this lengthy text.

- WHAT IS A SILENT CALL? - Why do they happen? - But why silence?

- WHAT IS OFCOM DOING ABOUT IT? - What Ofcom has got wrong - Latest Cases




- LINKS: - Ofcom Web Site - BBC TV Radio and News - Sound clips - DH Soundbites


Please send any useful feedback on this page to: Silent {dot} Calls @ ntlworld {dot} com


The phone rings, you pick it up, you may hear a little click, there is several seconds of (rather menacing) silence, the line goes dead.

Why do they happen?

It could be someone deliberately trying to upset you! .. but far more likely ..

Those making lots of "outbound" calls use "Automatic Calling Equipment" (ACE), also known as "predictive diallers", to avoid their agents taking time in dialling and waiting for you to answer, getting engaged tone or being connected to a fax or an answering machine or service. They aim to keep their agents busy, speaking to people all the time.

The computer equipment dials the numbers and only attempts to put calls through to an agent after a person has answered. If, when this happens, all of the agents are busy it results in what is now known as a "No Agent Available" (NAA) call. The current standard procedure for NAA calls, mandated by the Direct Marketing Code of Practice, gives you a period of silence before closing down the call. Many believe that transmitting a brief Informative Message would be a better way of dealing with a NAA call - see But why silence?.

Clever mathematics is used to work out how quickly the computer should do the dialling. No matter how clever it is, it cannot predict exactly when each agent will be ready for the next call or when, if ever, the currently ringing numbers will be answered.

This is not a question of getting the sums wrong or making mistakes, any more than choosing the wrong Lotto numbers could be said to be a mistake. Any use of predictive diallers delivers both considerable productivity benefits and a certain number of NAA calls.

Perhaps we should feel sorry for those who used to try to upset people by making silent calls - it does not work so often now!

What about VOIP and other reasons for technical failures?

It is suggested that the upcoming telephony revolution - use of "Voice Over Internet Protocol" - will make a major difference. I do not believe that this need be so. The essential nature of what is happening at either end of the line will remain the same, no matter how the signal is carried.

Whilst this technology is still in its infancy, audio failure is sadly both common and unpredictable. Steps will need to be taken by all parties involved to reduce the incidence of this before this technology could be accepted for everyday use.

Those advocating the use of VOIP have asked me to include the following comment.

"If you or a caller are using a Voice over Internet (VoIP) phone system, then be aware that problems that can sometimes occur, either in the (mis)configuration of the user's equipment or possibly server or other problems within one or more of the systems carrying the call. These may cause no audio in either direction, or one-way audio, where one party can hear the other but not the other way round.

"This can be entirely random and should not be taken as a deliberate malicious or silent call. This should not be seen as a reason not to use VoIP systems and take advantage of the services they offer."

To my mind, every caller has a responsibility to ensure that all aspects of the technology deployed are fit for purpose, whether this be the agent's headset microphone or the communications channel used.

But why silence?

I am still waiting for an adequate explanation for why a telemarketing company would want to make people scared of answering the phone. Any silent call to your home is unpleasant. Those who have not yet learned the most likely cause are left to wonder who it is that might want to upset or frighten them.

If NAA (No Agent Available) calls are an inevitable fact of life for telemarketing, there is no good reason (apart from the DMA Code of Practice) why they have to result in silence. A brief recorded message identifying the caller, a brief explanation and perhaps a contact number would seem to me to be the obvious alternative. A five-pound credit on your phone bill as compensation could be better, but a polite Informative Message would probably not be any more of a nuisance than the call was likely to be anyway. (It would certainly be better than one of the proposed alternatives - hearing silence and then being expected to dial 1471, write down the number, dial it and pay to hear the message.)

Many, such as the DMA, have falsely claimed that transmitting a recorded message is "illegal".

It is now clear that this is based on a misunderstanding of the provisions of Regulation 19 of the Privacy and Electronic Communications (EC Directive) Regulations 2003. The Office of the Information Commissioner, which enforces these regulations, confirms that an Informative Message, without any direct marketing purpose, is acceptable, even if the original intention of the call was direct marketing.

Whilst no-one would volunteer to receive a call that could not be completed because there was no agent available, I cannot see why anyone would prefer a Silent Call to a brief Informative Message. There can be no question that the vast majority, if faced with the choice between two options neither of which was actually desirable, would prefer the Informative Message.


On 2 May 2005 Ofcom used its powers under Sections 128 - 131 of the Communications Act 2003 for the first time to take action against MKD Holdings Ltd (known as Kitchens Direct) for making Silent Calls. This was in response to a complaint that I made and continue to pursue.

There is a good piece of video that was broadcast by the BBC on 5 May. This describes what silent calls are, covers the action taken in this case and includes a contribution from me. If you are interested in this case there is lots of stuff on the web. It is not over yet, so keep watching!

This case has thrown many aspects of Ofcom's policy into question, I cover some of these points below - What Ofcom has got wrong. This has become more important now that a further case including investigations into 7 companies has now been opened before these points have been resolved.

Perhaps the most important issue about Ofcom's policy is the suggestion and general mis-understanding that UK law has a similar provision to that in the US, which allows a "Safe Harbor" percentage of NAA calls. The UK Direct Marketing Association follows this principle by allowing its members a 5% "Safe Harbour" and has declared that this is supported by Ofcom. Ofcom has now given a clear statement on this issue, as follows: "there is no 'safe harbour' in UK law for calls at the level of 5% or any other level". The DMA has recently changed the wording of its Code of Practice to remove the reference to support from Ofcom on this point.

On 16 June Ofcom opened a new case covering investigations into 7 different companies. I believe that this will result in a major step forward.

Ofcom says that whilst these investigations are underway it cannot make any public statement on the subject of Silent Calls. It is however known to be in discussion with the DTI and the DMA on what must be determination of its policy to be applied in these cases. It has been pointed out to Ofcom that the provisions of Section 131 of the Communications Act require it to publish any changes to its general policy before it implements them. It would also be normal practice to engage in formal stakeholder consultation before any such change. Neither of these may be accomplished without public statements.

Those wishing to implement use of the Informative Message have asked Ofcom to confirm that it would not necessarily regard this as "persistent misuse" in the same way as it regards the Silent Call. We are waiting for Ofcom to respond to this reasonable request by making a public statement that can have no direct bearing on the current investigations as none of these relate to transmitting recorded messages.

I cover this latter point in yet another posting to OfcomWatch.

What Ofcom has got wrong

I will not go into full detail here, as I hope that the situation will change shortly. The initial Notification issued against MKD Holdings has the following flaws:

By the way in which this Notification was issued I believe that Ofcom has ensured that it will not be able to impose any penalty on this company. It has also set a disgracefully weak precedent for the new cases that are now following. Most significantly, whilst this company has been under some degree of control since May 2004, after the most appalling figures from early 2004, Ofcom will totally release all control from September 2005.

As stated above, I hope to be proved wrong, either as a result of some clever trick that Ofcom has hidden from me, or because it will shortly "get its act together" and deal with this case properly.

There is a posting on OfcomWatch that covers this in more detail:

New Cases

On 16 June Ofcom opened a new case covering investigations into 7 different companies.

These have been selected to represent a cross section of the types of offenders that need to be dealt with. I hope that they are also seen as the most suitable examples from each class.

I comment on the way in which these cases will be handled with reference to recent developments in a further posting to OfcomWatch

Broadcast and news coverage is found on links.

Who are these companies?

I have not been able to determine how Promote IT is involved in this.

Two of these are large classic UK telemarketing companies, members of the DMA, making lots of Silent Calls but aiming to keep within the 5% "Safe Harbour".

- The Listening Company Ltd

- ANT Marketing UK

Two of these promote their own services by telemarketing.

- Toucan Telecom

- Thompson Directories Ltd

Two of these are fax marketing agencies. It is likely that their calls are not caused in the same way as the classic Silent Call. They are probably either expecting the call to be answered by a fax machine or just testing to see if it is.

- Fax Information Services Ltd

- Firestorm Marketing Ltd

How did these cases happen - the information from BT

I cannot comment on how they reflect complaints from other sources, but am prepared to cover my part in these.

Having raised the issue initially in December 2003, in November 2004 I started working hard on both parties to get the BT Nuisance Calls Bureau to give Ofcom all of the information about Silent Callers that it held. Normally this would only happen if Ofcom used its legal powers to demand this in the course of pursuing a specific complaint in each case. BT could have had problems with the Privacy Laws in volunteering the information and Ofcom could not demand information without knowing what it was. BT was also reluctant to go to the trouble of checking out the "legals" and preparing the information in a suitable form without an assurance from Ofcom that it would actually do something "for a change".

I suggested that BT could provide the information in skeleton form, without identifying anyone so that Ofcom could then demand the detail. I understand that this idea was adopted, although only the final step is referred to in the Ofcom announcement. It is important to understand that Ofcom has, by this means, information about many other companies that it may move onto in due course.

Without anyone breaking any rules of propriety, I learnt that ANT Marketing was one of the companies on this list and pressed Ofcom to include it in its investigations. This company claims to be the largest of its kind in the UK and its Managing Director sits on the Direct Marketing Association Call Centre and Telemarketing Council.

How did these cases happen - the specific complaints

I cannot comment on Promote-IT.

I raised a complaint to Ofcom about Toucan Telecomm as this presents an interesting example relative to Ofcom using its powers for three reasons. This UK based company calls me regularly from overseas. The long pause before anyone speaks and the admission of the supervisor confirms for me that ACE is being used. I also receive many Silent Calls from a similar source that fall within the same pattern.

Being from overseas, these calls cannot be traced and so I could never prove that this company had made a Silent Call to me. Ofcom's powers allow action to be taken where it has reason to believe that someone is engaged in a pattern of behaviour "likely" to be causing the annoyance, inconvenience or anxiety that results from Silent Calls. I believe that anyone using ACE is involved in such behaviour. It is for the Ofcom investigation to determine whether the degree of nuisance being caused is worthy of action.

It is widely thought that companies can evade their responsibilities by making calls from outside Ofcom's jurisdiction. I cannot see why the location from where the call is made is in any way relevant. A UK company causing nuisance that occurs in UK homes must be subject to UK law.

The third point is the nature of the business being promoted to me by Toucan. In its role as a regulator of the telecommunications industry (rather than use of the telecommunications networks by anyone) Ofcom regulates and encourages the promotion of Carrier Pre-Select services. This service enables you to keep your BT line but pay for all your calls through another company. I am anxious to see that Ofcom does not suffer a conflict of interest.

The Listening Company called me at a time when I am prepared to believe that it suffered a technical glitch that led to no CLI being provided. This was not a Silent Call, that is how I knew who was calling and that the call was on behalf of BSkyB.

In correspondence with this company it has admitted that it makes Silent Calls, yet operates within the "safe harbour" of 5% specified in the DMA Code of Practice. I have pointed out that Ofcom does not endorse this code and, according to its published Statement of Policy, regards any "percentage approach" as being inappropriate to use of its powers. I have also been pressing this company to give serious consideration to use of the Informative Message, now known to be "legal" as an alternative to the Silent Call.

The Chief Executive of this company gave a most interesting interview to You and Yours on 17 June - see links.


The Direct Marketing Association (DMA)

The Direct Marketing Association is a trade association that represents all aspects of the direct marketing industry, it has no responsibility for regulation in the public interest. It seeks to represent those of its members who are involved in unsolicited telemarketing in two ways over the issue of Silent Calls.

Firstly, it has to ensure that formal regulation of the use of the equipment that causes Silent Calls is kept to a minimum as this restricts the scope of operation of its members. Secondly, because citizens have the option to isolate themselves from telemarketing, through use of the Telephone Preference Service, it should aim to minimise the number of people who opt-out by presenting the industry in the most positive light possible.

When the equipment that causes Silent Calls was first introduced, it was hoped that the nuisance of Silent Calls would not be recognised for what it is. It was feared that knowledge of this could lead to the equipment being banned in the public interest. For this reason, DMA members were required to keep the number of Silent Calls made at a level of no more than 5% of the total number of answered calls, measured over a 24-hour period.

This effort has been generally successful, in that the industry is now seen to be so reliant on this equipment that any attempt to ban it would, it is claimed, have serious consequences for jobs and an otherwise compliant industry. Even though the Silent Call is now widely recognised for what it is, there has been some success in re-defining the 5% limit as a public protection measure.

Recent action

In addition to the 5% rule the DMA Code of Practice includes a number of other measures relevant to Silent Calls, some of which have achieved a modest degree of adherence. Perhaps the most significant of these has been a requirement to always provide CLI (a return number) when making calls that could result in Silent Calls. This, along with other widely disregarded mandatory requirements, has been in place for several years.

On 15 June 2005 the DMA published a long-awaited report into the effect of Silent Calls - The Brookmead Report. This reported that 22% of the population experience anxiety when receiving Silent Calls and a further 37% regard them as an unacceptable nuisance. The report failed to give any indication of how the provision, or withholding, of CLI affected these experiences. It also failed to consider the option of the Informative Message as an alternative to the Silent Call.

As a reaction to this report the DMA, after four months private deliberation, re-announced the requirement for members to provide CLI. A modest revision to this requirement stipulated that the number provided should be a freephone number. Despite heralding this as a totally new provision and a significant move against Silent Calls in the public interest, this clearly indicates that the DMA has given up on defending call calling.

By this action, the DMA has effectively announced that it does not wish to take any action to save this aspect of the business of some of its members, for the sake of the direct marketing industry in general. As a private organisation it is quite entitled to take this position, although it cannot claim that it is seeking to address the problem of Silent Calls, when it has effectively given up. 


Following discussions with the Direct Marketing Association, BT has noted that the legitimate element of the telemarketing industry will not be doing anything to address the problem of Silent Calls. BT has therefore launched a service called "BT Privacy at Home", the main focus of which is seeking to encourage all of its customers to register with the Telephone Preference Service.

One benefit of this for BT is that it will stop other companies calling its customers to offer them cheaper telephone calls.

To make this more attractive, this service also includes free provision of the Caller Display feature, previously charged at 1.75 per month. Caller Display allows those using suitable telephones to see the number of who is calling when the phone rings.

This service is announced as having the objective of "crushing the menace of Silent Calls".

Caller Display can help by enabling one to see if the caller is recognised. It cannot, of course, tell if an unrecognised, or withheld, number indicates that the call is from a telemarketing company, or that the call is going to be silent.

A further increase in the proportion of the population registered with the TPS will have two effects. Firstly, it will focus the effects of telemarketing, including Silent Calls, on a shrinking number of people some of whom will be those most vulnerable to its effects. Secondly, once the number of those available to legitimate operators falls below the level at which the operation is commercially viable the work will pass to those who do not respect the TPS register, typically those outside the jurisdiction of the regulators.

I am not sure if this is what BT and the DMA wish to achieve!

I cover this point in a posting to OfcomWatch.

Members of Parliament and the Government

Since the inclusion of the relevant sections in the Communications Act many MPs have spoken about this and used parliamentary devices to advance the case against Silent Calls. The following refers only to the current parliament.

On 15 June John Hemming MP asked a question of the Prime Minister (hear a recording).

On 29 June the DTI announced an increase in the fines available to Ofcom and ICSTIS to deal with misuse of Premium Rate Services - a related but separate issue. The press release does however clearly link this move to a general DTI " drive to tackle nuisance calls" referring specifically to the Ofcom investigations into 7 different companies.

Before the summer recess, 46 MPs had signed Early Day Motion number 540 calling on Ofcom to use its powers to stop Silent Calls.

On 21 July Alun Michael, minister at the Department of Trade and Industry, answered a question from Mr Hemming about the Informative Message.

Mr Michael also covered his position on Silent Calls in a speech on 25 July.


This section deals with the limited measures that can be taken to deal with one's own position. I am campaigning to do all we can to stop all Silent Calls being made to everyone. Please read this and look at the next question also.

If you want to stop getting these calls yourself try registering your numbers with the Telephone Preference Service.

This should stop all cold calls, including more worthy activities such as charity appeals, and you will not ever be able to de-register your number. Once every useful UK number has been registered, then all cold calling will go underground and offshore and be totally un-regulated. So take a moment to think, before probably going ahead and doing it anyway.

Registering with the TPS may not be expected to stop Silent Calls from those who disregard regulations and overseas companies who cannot be covered by them. They may also be made by companies who believe that they have your consent to call you to tell existing customers about additional products and services. (Some fear that as TPS registration grows, this technique will be used even more than at present).

It will take up to 28 days to work and may not stop everything. Most UK companies do respect the list - see notes on Enforcement (this is not actually administered by Ofcom). There are mixed reports about the effectiveness of the TPS as a way of stopping silent calls to you - some say it resolved the problem completely, others say it made no difference.

Do not bother with Silent CallGard, very few companies use this. I have not heard any report of it being effective.

You may be offered other services for which you pay, such as Caller ID display, Choose to Refuse and Anonymous Call Rejection (ACR). Each of these has advantages and disadvantages that should be weighed on their merits, as well as having a direct cost. (Note: Caller ID display is now offered free by BT if you sign up for BT Privacy at Home. You will however need a telephone that displays numbers and to make some outgoing calls over the BT network).

Think carefully before using ACR - a lot of perfectly honest calls are made without giving a number, and this is often beyond the control of the person making the call. A friend calling from their workplace or from abroad, calls from many businesses such as employment agencies and even calls from anyone at the BBC are examples of those you could miss with ACR in place.


If you (perhaps also) want to "do your bit" to see Ofcom take action against those who are making Silent Calls to you, for the good of everyone - follow these steps. Please jump on to step 10 when you have had enough.

This applies only to the UK and calls made by, or for UK companies - Ofcom cannot act against companies outside the UK.

1. If you know the name of the company making the calls.

Go directly to step 8.

2. If there is a number given by dialling 1471.

You may want to spend some money by calling them to find out who they are. Whether you do or not - go to step 8.

3. If 1471 cannot give a number.

You are going to have to do a bit of work, be sure that you are up for it. If you are not, jump to step 10, now or whenever you change your mind.

4. Speak to the Nuisance Call Bureau (NCB) of your telephone service provider.

Ask them to enable the "call tracing facility" on your line.

They may need some persuasion. They can only do this for a limited number of lines, and must deal first with those who are receiving genuinely malicious calls. If you have been getting a regular pattern of silent calls, would reasonably expect to get more and intend to proceed with a formal complaint to Ofcom, then they should provide this facility.

The trace facility will only be provided for a limited period of time, perhaps one month. Be sure that you would expect to receive calls that need to be traced whilst you are in and ready to do the trace during that period. Make this clear to the NCB - they also want to see Silent Calls stopped and will be keen to help someone determined to do what is necessary to make this happen.

You must understand that they will not reveal the detail obtained from any trace to you, not the name of the company, nor even the number. They will reveal both to Ofcom.

The trace will only be applied to calls that you want traced, they will not be making a list of everyone who calls you.

Calls from overseas will not normally give a useable trace. Every call from the main UK network will.

5. Once the trace is enabled, you will have instructions about how to operate it.

This will be a series of numbers to dial after each call that you want to be traced has finished. Follow the instructions and keep a note of the date and the time of each traced call. Remember to do the trace immediately, before you make or receive another call.

6. You will need to speak to the NCB about each trace.

This is necessary to confirm that they have retrieved usable information. They may also tell you if they recognise the number as one from which lots of traced silent calls are made - this is very useful information.

They will not tell you the number or the name of the company.

Make a note of the reference by which they have recorded the information so that you can refer Ofcom directly to this record - this will normally be your number and the date and time that they have for the call.

7. I warned you.

8. Congratulations to those who came here directly - you are very rare.

9. Make a complaint to Ofcom.

You can telephone 0845 456 3000.

You can email the Ofcom contact centre.

You can try to use the Ofcom website.

IGNORE any messages or indications that Ofcom does not handle this type of complaint. LIE, if that is still necessary to get through the system, but apologise later for having done so necessarily. I am told that these apparent obstacles will be removed shortly.

Give Ofcom all the relevant information that you have. Any information held by your telephone service provider will be revealed to Ofcom on demand. If the caller's number belongs to a different provider, then Ofcom will go to that provider to get the name and address.

Demand that Ofcom obtain all the available evidence for this case by retrieving all relevant information held by all the telephone service providers about this company.

Ofcom has limited resources; it will use these wisely by only investigating those companies about whom it has the most evidence. Anything you can tell Ofcom about the company may help.

Ask Ofcom to keep you informed about the progress of your complaint. I hope that you will not have to go through what I have gone through in order for them to take action.

10a. Step 9 may not be necessary.

At my instigation, Ofcom will be regularly receiving a summary of the records from the BT NCB covering all the companies with the most cases of traced silent calls from the last few months. This has now been used to commence investigations into some of these companies - see New cases.

This does, of course rely on enough people doing the traces covered in steps 4 - 6, for all the major offenders to be identified.

10b. Step 9 may be even easier.

Ofcom's powers allow action to be taken where it has reason to believe that someone is engaged in a pattern of behaviour "likely" to be causing the annoyance, inconvenience or anxiety that results from Silent Calls. I believe that anyone using ACE is involved in such behaviour, as it is said that Silent Calls are an inevitable consequence of the use of this equipment. It is for the Ofcom investigation to determine whether the degree of nuisance being caused is worthy of action.

Whenever I receive a direct marketing call I aim to find out if it was made using a "predictive dialler". The first indication is a pause before the agent speaks. I ask the agent if an automatic dialler was used and if some calls end in silence. I also ask for the name and address of the company actually making the call. Sometimes it is necessary to speak with a supervisor to get all of this information. I would always conduct such conversations as politely as I can - these people are not themselves responsible for the nuisance.

If I feel that it is appropriate I will add the name of this company to my continuing complaint with Ofcom. This is what happened with Toucan, The Listening Company and ANT Marketing - see New cases.

Once Ofcom starts an investigation it can obtain the full history of the calls made by this equipment. It does need not a complaint to cover every silent call made. With Kitchens Direct, my complaint detailed only 2 traced silent calls, BT had evidence of more (perhaps dozens), Ofcom's investigation reported 1.5 million in a three month period.

My complaints about Toucan, The Listening Company and ANT Marketing did not detail any Silent Calls.

Ofcom tell me that they want more complaints, and I would only encourage those who want to go along the trail that I, and perhaps others, have cleared.

I should not have any special influence on Ofcom, if it will open investigations into companies named by me, there is no reason why it should not do the same for anyone else!

The very best of luck to you.

David Hickson