:::Jerry:::: wrote:

I would have thought that the BT network would monitor given ID numbers
against those from the true ID of the line being used for the call and at
the very minimum return a 'caller ID with-held' default cal back ID IYSWIM ?
Not to do so could, as you say, lead to the abuse of the system and open BT
and the various watchdogs etc. to all sorts of problems.

If they don't do the above something is very lacking IMO.


When I was working in a voice design for a few months i learnt a little
about CLI. It seems that there are 2 or three levels of CLI. One level
is the actual calling number and cannot (read: "really, really should
not") be altered / blocked / not passed. This level will be examined if
there are any investigations etc...

There is also a "information" level, this is the level that 1471 and
caller displays use. Subscribers can request that this is blocked or
use the 141 prefix (I think this is the number).

Additionally where a company obtains its telephony from one of the many
Other Licensed Operators they may choose to not present that level of
CLI or present a different number. Often this would be the front
reception desk for the building the call originated from or a central
operator for the company.

UK OLO's are required to log details of all call that come through there
networks, and keep these records indefinitely. (OLOs include BT, NTL,
C&W, Global Crossing, Energis, O2, Orange etc...).

CLI is an international system, but of course some countries do not
stick to the system, and there are ways of hacking the system. In
particular phones companies in Las Vegas _have_ had a doggy reputation
recently (mainly to do with diverting callers to alternative adult
services etc.). Also there have been some concerns about the security
of VOIP (voice over IP) and IPT (IP telephony), where it's been found
quite easy to make calls and spoof the CLI.

00000000 was probably a call from a company "managing" it's own PABX.
If it was a malicious call it probably could be traced.

If it was from outside the up it probably wouldn't have presented any
number.

hth
--
peter