posted on Oct, 19 2005 @ 09:00 AM
Originally posted by Icarus Rising
The article said they don't have dedicated circuits like they did in the old days, and with digital technology, multiple calls can now be carried on
what amounts to the same 'line'. Their equipment isn't sensitive enough or calibrated properly or whatever to pick out only the targeted
transmission. At least that was how they explained it.
The article is a little incorrect I feel. I work in a Voice fault capacity for a large Telecoms firm in the UK.
A normal telephone line (PSTN) will be a 64k circuit, which is about the right bandwidth needed to transmit human voice traffic.
Even when it reaches the exchange, that PSTN line will go into the switch and be pushed out either on a IMT (intermachine trunk) to another switch in
the network, or if going to another network, via an interconnect.
Even when going down large "trunks" that can have a quite a large bandwidth, the "call" is presented on one 64k channel. That is how all circuits
are built, from 64k upwards.
It shouldn't be too difficult to single out one channel and "eavesdrop", providing you have access to the switches.
The very nature of switched telephony needs a "circuit" to be established from point a to point b, That is how the call is transmitted.
They are making up a load of bull if they are blaming it on "digital" technology, as it should make it easier.
What they have done is listened to the wrong channel due to someone being a monkey. Failing listening to a call at the exchange level, it is as simple
as connecting a phone into the copper cable that connects the phone to the DP/exchange. You could probably connect a speaker up to the twisted copper
pairs and listen to the call that way.
Not rocket science folks. DMS switching has been around for donkeys and the PSTN even longer.....
Plus, from the property to the exchange (or DP, I forget which), a normal PSTN line would be analogue anyway.