A number of mainstream carriers and call providers as well as NGN suppliers are using the DNIS service to prevent people dialing the geographical number direct.

DNIS in short is-

Dialed Number Identification Service

Basically, when you dial a number, the carrier receives the number you've called, and can route those calls differently, an example of this is

A call to ABC-Bank on 08701234567 diverts to the geographical number of 01131234567, of course dialing the 01 number is going to be cheaper, but those companies who are implementing the DNIS will receive the dialed number in whats called the ANI part of the call, thus will allow the company to see which number was dialed and treat those calls differently to those calling the NGN.

So calling the 0870 will enter your call into the call queue but dialing the geographical number will result in the call handled in which ever way the company wishes, even enabling them to announce number out of service or some other recorded announcement.

I'm a telecoms engineer for a large carrier and we have been provisioning the DNIS for a number of commercial house-hold name businesses, although it is my job (and of course my source of income) so I sadly can't disclose the businesses which have implemented this service, with this, a number of the geographical numbers may cease to connect even though it is effectively still the correct number where the termination is configured to.

I still 100% support that of SNT0870 and use it myself!

One can see practical uses for DNIS where calls from different sources are directed to a common destination.

Is is seriously being suggested that it is being deployed to prevent direct dialling to destination numbers?

SilentCallsVictim,

Some of the businesses which have so far requested implementation and have the service available to them now, generate that much revenue on NGN's the companies are prepared to do what it can to protect the extra income it receives.

These businesses are from a mass of household names, from financial institutions and utility companies to entertainment.

Of course i'm all for businesses using technology for the better, but not to fleece the customer as it is those very customers who are keeping them in business.

I've use this myself, albeit in a more consumer-friendly form..

When we sold on ebay a lot we had an 0870 contact number (sorry!) that was set so that calls forwarded to the normal house phone came up with the 0870 on the caller-id.  That way I knew if it was a business or personal call.  I had tried using the BT Call Sign to get us a different number, but it didn't work properly with the phones we had at the time.

I also set up a system recently where unwanted withheld callers would be told to redial an 070 number, which would actually come back in on the same line, but the caller-id, set with the 070, would identify the type of call for processing differently ...

Obviously in both these cases, dialing the 01 number directly (without a 141..) would bypass all this.

irrelevant,

I here what your saying, but it sounds more like "Reverse Call ID" is what you used, as DNIS is part of SS7 signalling, and alot of businesses these days also have the own SS7 switching equipment, and so long as they've signed an agreement with the inbound carrier, calls with a privacy flag (withheld/141) CLI is still received in full allowing the business to view withheld CLI, just the same as calling BT or T-Mobile for example, these companies will still receive your CLI regardless if it is withheld, it is allowed too as businesses use it to obtain the geographical information of where it is receiving calls from.

An example of this is utility companies use this information to record trends, such as LocalElectric starts to receive a high number of calls from people connected to the 0131560 exchange, it can indicate a power outage or other fault, so before even answering any calls it could be safe to assume of a problem in that area.

Yes that sounds like an appropriate name for it.  Nothing special needed at my end (hence the "consumer-friendly" referance.)

I am concerned, however, that you are saying that some companies can be given a caller's number even if it's been specifically withheld.  That sounds like it's a breach of T&Cs somewhere..

Don't take the CLI out of proportion, only the companies with the own SS7 switching equipment are able to do this, and it isn't your everyday company, although most call centres if not all have this equipment to handle the trunk lines coming in from the carrier.

Another thing, withholding CLI is and never was designed to be totally private, as each carrier needs to pass the CLI and ANI data onto each other during the call setup leg.

This has and always will be the case, as that information is required on the receiving swtich to be able to route the call and log in the CDR correctly, the sending switch simply tags the CLI with a privacy flag which the receiving switch on the interconnect is to ethically honour the flag and not reveal the CLI to the end user, a user with the own SS7 switching equipment will also receive the CLI with the privacy flag enabled.

Once upon a time when calling to a number of international destinations even with 141 prefix the CLI was still been displayed, as the UK's CLI is PRI-ETSI(UK) basically none standard, and some international switches didn't understand the privacy flag. This problem only effected calls originating via BT Switches, Cable and other Teleco switches didn't do this, BT however now do not process any CLI on international inbound/outbound calls, except operator connect calls.

Hobbie wrote on Oct 14^th, 2008 at 6:39pm:

Some of the businesses which have so far requested implementation and have the service available to them now, generate that much revenue on NGN's the companies are prepared to do what it can to protect the extra income it receives.

We agree that it is unacceptable for companies to "fleece" customers, and that some appear to have this intention.
There are many ways in which technology provides the means for this to be done.

I asked if there is evidence that DNIS is actually being deployed to this purpose.
Is this thread simply alerting us (and NGN users) to the possibility?

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CLI is quite different, because it raises privacy issues that do not exist with DNIS.


Hobbie wrote on Oct 14^th, 2008 at 7:47pm:

Don't take the CLI out of proportion ... withholding CLI is and never was designed to be totally private

Some sense of proportion is provided by regulation 10 of the Privacy and Electronic Communications Regulations 2003.

If there is evidence that this is being breached, it must be presented to the ICO.

SilentCallsVictim wrote on Oct 15^th, 2008 at 12:00am:

Some sense of proportion is provided by regulation 10 of the Privacy and Electronic Communications Regulations 2003. If there is evidence that this is being breached, it must be presented to the ICO.

Also in that act, in section 14, is a prohibition of processing of the location of the caller, unless they have specifically given their permission beforehand.  This seems to imply that the uses Hobbie is suggesting are already being made of the numbers is also in breach of the rules.

Isn't this what National Rail Enquiries does when you use their International number.

irrelevant wrote on Oct 15^th, 2008 at 6:27am:

Also in that act, in section 14, is a prohibition of processing of the location of the caller, unless they have specifically given their permission beforehand.

Not quite. 14.2 is broken into two parts.

In part (a) There is no prohibition "where the user or subscriber cannot be identified from such data".

It is therefore perfectly acceptable for a call to be directed to a call centre covering the general geographic area from where the call was made, or for the general location of the caller to be made available to the person receiving the call.

When you phone your partner to say that you have been kept late at work, you can conceal the precise place you are calling from, but not the general location. Choose a pub very close to the office.

Part (b) requires consent where a value added service is to be provided.

It must be noted that regulation 14 (like 10) covers the activities of Telcos. In the case of mobiles, it covers the cell from which the call was made.


We are however drifting off-topic, as we are supposed to be discussing DNIS. I cannot see any privacy implications with this. The dialled number is clearly information that one is happy to provide, having chosen to dial it.

SilentCallsVictim wrote on Oct 15^th, 2008 at 12:00am:

I asked if there is evidence that DNIS is actually being deployed to this purpose. Is this thread simply alerting us (and NGN users) to the possibility?

Yes a number of businesses ARE using DNIS now, and are playing announcements to those who dial the geographical number informing them to redial the NGN number.

So even if you are successful in obtaining the actual correct geographical number, it will by no means work any longer unless the call is made internationally, which some CPS service providers do route the call internationally as it is usually cheaper, then in that case the DNIS is never provided and thus no way of detecting the dialed number and the call would connect as "normal".

Hobbie wrote on Oct 15^th, 2008 at 2:38pm:

Yes a number of businesses ARE using DNIS now, and are playing announcements to those who dial the geographical number informing them to redial the NGN number.

Thank you.

This is very useful information in the context of the database. It would also be useful if alternatives to which this is applied could be flagged or deleted.

Saynoto0870 is however not just a database. It is a campaign against the improper use of revenue sharing numbers. This may be because the context is inappropriate (e.g. for public services or complaint lines) or because the cost of calling is not properly advised. Some would say that there is no proper use of revenue sharing numbers.

Use of unpublished alternatives is just one way of undermining improper use. The purpose is to get propriety re-established.

Those who have a valid need for a non-geographic number now have 03xx as an option that denies revenue share and gives an assurance of no call rate surcharge.

There are many situations where unpublished alternative numbers are not found or are unsuitable, e.g due to use of DNIS. This is no defeat for SNT0870, the campaign must go on.

SilentCallsVictim wrote on Oct 15^th, 2008 at 4:17pm:

Saynoto0870 is however not just a database. It is a campaign against the improper use of revenue sharing numbers. This may be because the context is inappropriate (e.g. for public services or complaint lines) or because the cost of calling is not properly advised. Some would say that there is no proper use of revenue sharing numbers.

Whether a revenue sharing number is properly utilised or not can only be judged on what the price is. They are not "normal" rate numbers as they attract a significantly higher termination rate than for geographical calls, but yet the call ends up on a landline. So retail prices must be openly declared, which is often not the case for 084 and 087 numbers.

Furthermore, the premium charges for the service apply from the point of the call being answered and throughout the menu and queuing process. So the payment depends on the length of the wait before one can speak to a human (assuming that that is the point of the service).

The customer cannot know how long it will be until they actually get through to the thing that they are paying for whilst waiting. How many of these companies are busy installing systems to tell the caller how many people are in front of them in the queue, an estimation of the time they will have to wait and a facility for them to be called back when someone becomes available?

It seems to me that this is something only a small number of companies will do: large companies with a certain sort of telephone equipment. It also seems that it may be possible to cirumvent by using certain dial through operators because of the way their calls are routed, or maybe using certain VoIP services.

Any company who tells people calling them on a particular number that they shouldn't do so - whether through a system like this, or through an Aliance & Leicester-style interrogation - is simply revealing their true motive for implementing revenue-sharing numbers: to make extra profit. The best solution for saying NO to 0870 numbers in this case is to take your business elsewhere. If that's what our campaign needs to concentrate on, so be it.

VoIP terminating to the PSTN does not send DNIS Information (but receives) so calling these numbers via a VoIP provider that uses SIP or some other technology including Skype would get around this.

Of course a number of other methods is also available, as previously mentioned using a CPS carrier, calls via a callingcard, basically anything that redirects the call for you where you do not dial the number direct.

At present, the businesses using it are only large entities that I am aware of, ie. those that I have been involved with, one of the biggest is well discussed on SNT0870.

jrawle wrote on Oct 15^th, 2008 at 10:13pm:

The best solution for saying NO to 0870 numbers in this case is to take your business elsewhere.

Exactly.  As more and more companies and organisations start providing geographical (or 03) numbers, and as more and more people become aware of the charging issues, business will shift naturally.

There are three banks in my nearest town: one allows you to call the branch and the other two use call centres (one even redirects mail to a central office).  Guess which one I've transferred my business to and recommend to others!