Hi Jeff
If we're both assuming "Line Jack Sockets" are one and the same thing, then absolutely yes.
As I've mooted previously, there HAS to be a demarcation between 'our' wiring and 'your' wiring.
This *demarcation point* will be the first socket that is connected to the BT Openreach wiring that enters the premises. If it isn't an NTE5-type socket, (whereby there is a detachable front plate that all extention wiring should be connected to), then it will be what I would call a 'Line Jack Socket'.
If you have this old-type set up, you are quite within your rights to ask your SP to make an appointment for us to attend F.O.C. to bring the installation up to par. A couple of reasons are, 1) That you need to isolate some or all of your extention wiring to gain a faster DSL speed, or 2) You have purchased a Service Specific Front Plate (ADSL Nation, etc) and without an NTE5, it is impossible to legally fit it.
I hope we're talking about the same thing here Jeff, and I don't mean to sound like I'm teaching my granny to suck eggs, just thought I'd try and make it clear for the folk out there who are unsure.
*The latest New Build properties actually have the demarcation point OUTSIDE the premises, bringing us in line with the Gas,Lekky and Water industries.*