With the benefit of a famous geek contributing to the forum, one must ask a commonly encountered question.

It is suggested that facilities such as "network waiting", i.e. queuing calls at the exchange rather than occupying lines to the destination, are only, or more readily, available on non-geographic, rather than geographic, numbers. Automatic switching is another feature said to be provided.

There are however examples of cases where very large queues are handled on geographic numbers and call re-direct is a standard feature available on normal lines. These examples are often used to refute the suggestion that there is any technical benefit to having a non-geographic number.

If there were no technical benefit, then the only justification for the considerable expense of a 03 number would be geographic anonymity. I am therefore inclined to believe that there is some technical benefit and this is not, as some suggest, just a myth put out by those who make money out of revenue sharing.

An expert comment on this issue would be appreciated. Do non-geographic number offer technical benefits over geographic numbers?

SilentCallsVictim wrote on Jul 2^nd, 2011 at 3:05pm:


I Didn't think I was famous! I only have what, 6 posts to my name.

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Well when you get into the world of digital services then you can do all those things against any old number. Swithing etc (See my item about DDI re-mapping above) can all be done, but at a cost.

If you went to BT I don't actually know if they would even give you the option to re-map numbers on the fly - or if they did there would (I suspect) be a huge cost attached to it. Just because we can do it at work, that just says the back end systems will let us, not that its a given right/option for any member of joe public to buy.

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Indeed as I said up thread, there is no limit (That I can recall) of how many channels you have coming into your phone system. There are issues with divert and some enhanced services I suspect these are BT (or your carrier of choice) problems rather than technical problems as such.

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There are - its *much* easier to manage a non geo number in the grand world of telecoms - you don't have to worry about re-writing the routing tables for 1 number bang in the middle of a range. (If you do internet/networking as a job you can relate this to eBGP prefixes being advertised as the largest block you can, rather than every individual address or /32)

By virtue the non geo number is routed to 'someone' the bigger PTN (Public telephone network) doesn't have to worry about much more than getting the call to the hand-off point. What happens after that depends on the non geo provider. (I'm generally talking about providers with there own SS7 switches and things)

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I wouldn't call myself an 'expert' but I would say I'm fairley clued up on this stuff. There are going to be people out there who have worked for PTN's for 20 years just twitching to point out any errors I've made! I'm happy to point people in the right direction, but at the end of the day if your that interested in something start looking into it a bit deeper, there are lots of forums for telecoms people, and NNTP is still alive (I think)

A good example of network routing in the PTN world was shown on Sept 11th in the US. After the buildings came down an entire city number block got wiped off the AT&T network. At the time AT&T where still pushing calls towards the outlying nodes (or if you read my stuff up thread DJSU's in our case) those nodes where not able to progress the call to the end user, or any leaf node and would therefor jam every turnk line in and out of the city trying to route calls when there is no point. AT&T picked up on this and actually pulled the routes to the 'lost' number blocks from the entire network - in doing that it halted *every* attempt made to an invalid number from getting any further that the exchange it originated at.

E.g:

You are based in 01332 2 (Derby) and your trying to call 020 7484 (London) your call will transit the network till it hits the 020 cloud at that point your routed to the exchange its self (in this case 484) the exchange then connects you to the EU (End user) Say the 484 exchange fell into the underground and was forever lost - your call would still make it to the 020 cloud before it knew that 484 was gone and gave you the error tone, if everyone did the same thing soon the 020 cloud would be clogged. If you pull the datafil over the entire network for 020 7484 then anyone calling that would get the out of service tone soon as they entered the last digit of the above prefix - thatway the call (or its setup) will ever leave the 01322 2 exchange or node. Either way it cuts down the ammount of 'stuff' sent.

derrick wrote on Feb 9^th, 2011 at 9:45am:
Well I did ask, and got what I expected. Some excerpts from the Decision Notice:

1.
The complainant has requested the underlying geographical telephone number for Transport for London’s (“TfL”) 0843 travel information line. TfL withheld this information on the basis of the commercial interest exemption (section 43(2)).
2.
The Commissioner’s decision is that TfL was correct to withhold this information under this exemption.
3.
Therefore Commissioner does not require TfL to take any steps.
10.
The commercial interest exemption states that information is exempt if disclosure would or would be likely to prejudice the commercial interests of any person (including the public authority holding it).
11.
In this case the requested information relates to the main telephone number (0843 222 1234) for the TfL Transport Information Centre's helpline.1 The request is for the geographical number that underlies this 0843 number. TfL has explained that there are, in fact, a number of geographical numbers that underlie the 0843 number.
12.
TfL has withheld this information on the basis that disclosure would be likely to prejudice its commercial interests.
13.
In reaching a view on the application of this exemption the Commissioner has first considered whether the potential prejudice argued by TfL relates to the interest identified in this exemption – i.e. if the prejudice were to occur, would this prejudice relate to the commercial interests of TfL?
14.
TfL has informed the Commissioner that when a caller rings the 0843 telephone number, depending on the nature of their query, the call may be routed through one of several different geographic telephone numbers across multiple sites. It has further explained that, "Each of these call centres is run by one of several different suppliers on our behalf, each of whom deals with different aspects of London travel (e.g. bus enquiries, London Underground, refunds, etc). Each supplier is paid according to the number of calls handled." It has argued that if the withheld information were to be disclosed, this would result in calls being made to the wrong sites, which would require calls to be rerouted to the correct call centre. As each call centre supplier is paid according to the number of calls handled, this would result in increased costs to TfL.
15.
The Commissioner considers that the relationship between TfL and these service providers is of a commercial nature, in that it relates to the costs incurred through a commercial contract. Bearing this in mind, he is satisfied that the potential prejudicial effects argued by TfL do relate to its commercial interests.
16.
In addition to this, bearing in mind the above arguments, the Commissioner is satisfied that there is a causal relationship between the potential disclosure of the withheld information and prejudice to the commercial interests of TfL. Furthermore, he is satisfied that the resultant prejudice (if it were to occur) would be real and of substance.
17.
Next the Commissioner has gone on to consider whether the disclosure of this information would be likely to prejudice the commercial interests of TfL.
18.
In reaching a decision on the question of the likelihood of prejudice the Commissioner considers that the expression ‘likely to prejudice’ means that the chance of prejudice being suffered should be more than a hypothetical possibility – there must be a real and significant risk.
19.
As noted above, TfL has informed the Commissioner that when a caller rings the 0843 telephone number, depending on the nature of the query, the call may be routed to one of several different call centres. Calls are routed to the correct call centre by the use of an Interactive Voice Response system ("IVR system") on the 0843 number. The call centres are run by different call centre suppliers, which handle calls on behalf of TfL in relation to specific aspects of London travel. TfL pays each supplier according to the number of calls that are handled by that supplier’s employees.
20.
TfL has argued that if the withheld information were to be disclosed there would be a significant chance that callers would call one of the geographic numbers (i.e. the withheld information) rather than the main 0843 number. It has referred the Commissioner to various websites promoting the use of geographic numbers, rather than central 08 telephone numbers, in order to support this argument.
21.
Without the IVR system in place to route calls to the correct call centre, given that there are a number of geographic telephone numbers that underlie the 0843 number, there would be a significant chance that many calls made directly to the geographic numbers would be made to the wrong call centre. These would then have to be rerouted to the correct call centre. The net result of this would be that two call centre suppliers (both the one who had received the incorrect call and the one to whom the call was redirected to) would then both be able to bill TfL for the handling of one call.

/cont...

idb wrote on Sep 28^th, 2011 at 11:34am:

What is potentially interesting about this decision is that the commercial interest which is deemed to override the public interest in disclosure is not that of the subsidy obtained from the revenue share on the 0843 number.

This case hinges on the fact that there is no direct one-to-one geographic equivalent number. Fans of FOI requests (I am not one) may be interested to attempt to pursue cases where there is expected to be a direct relationship between the Business Rate number and an underlying geographic number.

There is another interesting request in progress (and very very overdue) which may shed a little light on some of technical aspects of the system & call centre setup. Including specific questions about revenue, and call times from landline & mobiles.

Yep - I know this was an old post but still. Also the FoI enquirey I pointed out has been fully answered now along with info on the ammount of money TfL pay who to operate the phone systems.

They have a 240 inbound Call limit... Interesting