Anyway, the way ADT alarms are installed is basically to hardware to the incoming cables, i.e. NOT to the extension prongs of the master socket if it has such an arrangement. I was once told this was to prevent an intruder from being able to disable the connection too easily, and to prevent the owner from accidentally disabling the alarm connection. I don't know if this is 100% accurate or not.
I think I can also see why the installation engineer would not want to touch it, as it would cause the alarm to be disconnected/disabled and he would not be able to know if it was correctly re-connected once he had finished his part.
As to the speed issues - as things stand, the alarm modem (or digi/dialier as they sometimes call them) is unfiltered, and since it calls home every time you arm/disarm there are going to be problems from that.
Once the ADT engineer has visited and filtered it then it should be fine and your speeds may improve.
I seem to remember being quoted £60 or more to have an alarm filtered at one point in the past, so be prepared for a bill (depending on your ADT contract type).
It's just connected like that so the enduser does not disconnect it by mistake. Most modern alarm panels will default to mobile phone network if the line is interrupted.
If this were my line I would disconnect the panel from the A and B connections on the master socket (it's connected there along with the incoming line) and connect it to the filterd output of the VSDL plate Job done.
Edited by systemx (Thu 08-May-14 18:04:38)