Sorry if it's been asked before but it's an important question and many new arrivals would get a chance to read it again without digging for old threads if it has.

In my experience using a geographical alternative has always worked for me, but I read here that some firms claim using the geographic number will go to a different place and get poorer service. I was under the impression 08 numbers masked and diverted to an existing number (many companies stupidly advertise them to attract foreign customers not realising they've just given away their cheap number to us as well).

If this was not the case companies could simply screen calls not using the 08 numbers and refuse to answer them.
So my simple question is a) can the companies spot whether someone's used their real number to call or not? leading to b) can they set up 08 numbers to different operators from the local number or is it really like the TV detector vans which actually contain a list of addresses and tea making facilities rather than TV detectors (so I hear) and in fact it's impossible to tell but they don't want us to know it?

I think that you are pretty much asking "how long is a piece of string?"

In some cases the alternatives on our site might not be the actual geographical numbers that the NGNs point to. It has also been suggested recently that they are provided with the number the caller dialled. So there is no way to give a definitive answer to your question.

I'm sure the poster who claimed he could here would disagree ;)

I suspect sometimes secrets get mentioned in passing, but far more often they are not secrets but smokescreens.

If the technology exists to show if a caller is ringing the same phone to their geographic number or not then it's a simple yes or no answer.

I may have been guilty of hiding a simple question in a lecture but I'm prone to doing that. I hope I've simplified it now.

I'll add c) IF they can tell, what would indicate it? Would a light come up on the phone to show it's coming from elsewhere like in the James Bond films as although you can get caller ID flash up it only shows their number, not yours. Or does it...

Elsewhere on the forum it has been mentioned that some telcos have implemented so-called "Dialed Number Identification Service" (DNIS).

I would say it's the larger companies. A local insurance broker or small mail order company probably won't be bothered what number you dial.

At work, the senior managers' phones redirect to their shared PA after a few rings, and she always answers to say it's the office of whoever the caller was trying to contact. She has a phone with a multi-line display, and although I've never seen it, I presume it says what number the call was forwarded from. That not really any different from the call being forwarded from an 08 number.

However, I still suspect in most cases the companies known when a geographical number has been used as it goes through to a different office or phone.

Thanks Dave, you seem to be everywhere at the same time, or do you have lots of different Daves? So they can tell after all. I hope it doesn't allow more to block when called on different numbers to the one advertised.

David_H wrote on Dec 12^th, 2008 at 4:30pm:

Thanks Dave, you seem to be everywhere at the same time, or do you have lots of different Daves? So they can tell after all. I hope it doesn't allow more to block when called on different numbers to the one advertised.

Yes, I am everywhere at the same time!  ;D

I certainly think there are some out there who shut down any alternatives to circumvent the premium charges. Alliance & Leicester must come top of that list as this thread started by a customer who was "banned" shows.

David_H wrote on Dec 12^th, 2008 at 4:30pm:

Thanks Dave, you seem to be everywhere at the same time, or do you have lots of different Daves?

I think you may well have hit on something there.  There is another forum moderator called DaveM but for years both he and Dave had forum avatars both showing men wearing the same white lab scientist coats.

In my observation Dave is the main forum moderator character and DaveM usually seems to be used when a more critical or hostile forum post needs to be responded to.

There was also another moderator for a while called bbb_uk but in the last few months he seems to have largely faded away while Dave seems to have become more ominpresent in the forum than ever.

jrawle wrote on Dec 12^th, 2008 at 3:11pm:

At work, the senior managers' phones redirect to their shared PA after a few rings, and she always answers to say it's the office of whoever the caller was trying to contact. She has a phone with a multi-line display, and although I've never seen it, I presume it says what number the call was forwarded from. That not really any different from the call being forwarded from an 08 number. However, I still suspect in most cases the companies known when a geographical number has been used as it goes through to a different office or phone.

A company I used to work at had about eight lines into the building split across the main office number, a tech support number, and two lines for a separate tenant.  All lines rang on all phones, but a display showed us the name of the line group called, so we could ignore or answer appropriately. (ie only tech support used to answer the tech line, unless it rang too long because they were all busy, and we all ignored the tennant's lines unless they were out, in which case our reception would take messages.)  All on geographic POTS numbers of course.

David_H wrote on Dec 12^th, 2008 at 12:24pm:

can the companies spot whether someone's used their real number to call or not?

Yes. The number that was dialled is provided to companies' phone systems with each incoming call that is offered. That's how DDI works - all incoming calls share the same (virtual) lines and the phone system needs to know the number dialled to ring the right extension, or to tell the network that the number is busy if all extensions allocated to the number are busy or DND. So a call dialled to the geo number can be routed to the 'foreign calls' department and the caller's number will show that it is not a foreign call.

So what happens if you prefix the number you dial with 141?

pw4 wrote on Dec 17^th, 2008 at 2:35pm:

David_H wrote on Dec 12th, 2008 at 12:24pm: can the companies spot whether someone's used their real number to call or not? Yes. The number that was dialled is provided to companies' phone systems with each incoming call that is offered. That's how DDI works - all incoming calls share the same (virtual) lines and the phone system needs to know the number dialled to ring the right extension, or to tell the network that the number is busy if all extensions allocated to the number are busy or DND. So a call dialled to the geo number can be routed to the 'foreign calls' department and the caller's number will show that it is not a foreign call.

I'd say that this is quite possible, on the more sophisticated systems that actually terminate the NTS numbers directly.  For the vast majority of users, though, the operators switch 'translates' (hence the T in NTS) into the underlying geographic number of the subscriber, and it's that which is presented to the subscriber's PABX.  And even then, it's only ISDN or VoIP connections that allow presentation of the DID number - standard analogue POTS lines only allow for the callers' ID to be presented**, as each line has it's own physical number (unlike the others, where numbers are not directly tied to an connection.)  

Of course, it's quite possble for an NTS number to terminate on a particular number, and the published 'international' geographic number to be a completely different number.  So, simply because of the lines/DID number that the call rings on they know pretty much which you dialed.


** There are suppliers (eg Flextel) who can provide you with a non-gegraphic number that presents the NTS number dialed in place of the callers' numbers, but then you've lost the information on who is calling, so it's only of limited application.

sherbert wrote on Dec 17^th, 2008 at 2:54pm:

So what happens if you prefix the number you dial with 141?

This is irrelevant in the case outlined above.

If my phone number is 01234 567890 and I dial a company's "overseas" number, 020 3456 7890, their equipment will flash up with the fact I dialled 02034567890. It may also show that my number is 01234567890, which they will know isn't an overseas number. Using 141 will stop the latter, but not the former. Ultimately, their equipment will know what number the call came in on. This isn't something that can be concealed by the caller.

jrawle wrote on Dec 17^th, 2008 at 3:48pm:

sherbert wrote on Dec 17th, 2008 at 2:54pm: So what happens if you prefix the number you dial with 141? This is irrelevant in the case outlined above. If my phone number is 01234 567890 and I dial a company's "overseas" number, 020 3456 7890, their equipment will flash up with the fact I dialled 02034567890. It may also show that my number is 01234567890, which they will know isn't an overseas number. Using 141 will stop the latter, but not the former. Ultimately, their equipment will know what number the call came in on. This isn't something that can be concealed by the caller.

Thanks for your answer jrawle

jrawle wrote on Dec 17^th, 2008 at 3:48pm:

If my phone number is 01234 567890 and I dial a company's "overseas" number, 020 3456 7890, their equipment will flash up with the fact I dialled 02034567890.

But if you've withheld your number - so you don't send a UK CLI - and called in on their overseas number, how will they know you're not correctly calling on the overseas numer?

Similarly, if you use 18185, only 'international' is sent as a CLI anyway, so that'd defeat this type of system too.

Now I see what sherbert was getting at. If they don't know you are not overseas, they might not mind you calling the international number. However, if some other detail gives away the fact that you are in the UK, hiding the CLI won't do much good!

In my experience, international CLI is unrelable. On a few occasions, calls originated to the UK from here in FL will present some given London number as oppsed to INTERNATIONAL, UNAVAILABLE or something else. Occasionally they present as WITHHELD, even though I never surpress my number. Additionally, incoming calls from the UK may show a garbled attempt at CLI, for example, 441 is the NANP area code for Bermuda, so a call from, say +44 1234 567890 will show as HAMILTON 441-234-5678 or BERMUDA 441-234-5678 on my AT&T line. Sometimes the CLI will present with a generic number from a given city, eg ATLANTA, GA XXX-XXX-XXXX or NEW YORK, NY XXX-XXX-XXXX, which aslo presents on many calls made domestically from AT&T calling cards.

One other aspect to remember is that, from a UK perspective, the prfix 141 does not actually withhold the number; rather it is an instruction for the end/terminating equipment to surpress the calling number from being displayed on a subscriber's system - an important distinction. I vaguely recall in the early days of caller ID, there was a service based out of the Netherlands (I think it may have been called Xoip and had some form of callback function) that routinely ignored 141. Clearly a violation, but nevertheless it happened. I'm sure there were other examples.

irrelevant wrote on Dec 17^th, 2008 at 3:29pm:

For the vast majority of users, though, the operators switch 'translates' (hence the T in NTS) into the underlying geographic number of the subscriber, and it's that which is presented to the subscriber's PABX.

Right - so it is the translated number that is forwarded. Thanks for the correction.



Quote:

Of course, it's quite possble for an NTS number to terminate on a particular number, and the published 'international' geographic number to be a completely different number.  So, simply because of the lines/DID number that the call rings on they know pretty much which you dialed.

That makes more sense. So to identify the calls dialled to the NGN, they could be translated to a DDI number that is not used for anything else or made known - even to employees - and then routed or displayed accordingly.