Oops someone has been a bit lapse
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In answer to the questions he asked
Is this a DSLAM?The photo is actually of Fujitsu line cards.
IS-LCSS would indicate a relatively old type DSLAM.
iirc BT started using the newer
IV-LCSS (4th gen) line cards at around the time of maxdsl (2006 ish) although some of the older ones are still in place in some exchanges, they definitely wont be able to sustain a 21CN line.
Bit surprised they were able to be photographed so easily, they are usually in a unit with a front cover on.
What is a LDU?Loop Diagnistic Unit. Provides local loop line test facilities, such as the Quiet Line Test etc.
what are these? No idea, some sort of card on the POTS (System x/System Y)?
>> this I believe is the "local loop frame", Its the MDF (Main Distribution Frame). Looks like a very small exchange.
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More info on most of the above can be seen on the page
Inside the BT exchange.
Although Ive cropped off the LDU's on the photo for the site, they were under the DACs monitor unit, and you can just see the tops of them.