I was just doing a sweep of eBay, to see what sort of prices are being asked for the new NTE5/C & the NTE5/C plus Mk 4 filtered faceplate, when I came across an item advertised as --
Genuine Phone Master Socket NTE5a +Back Box +IDC Tool. COMMMTEL for BT Openreach
-- with a sub-heading of --
MADE IN THE UK FOR BT BY RATHDOWN INDUSTRIES LTD.
Looking at the images it most certainly is not an "NTE5a", nor is a "Back Box +IDC Tool" visible.
It appears to have the standard BT 631A socket under a shutter on the front and the equivalent plug on the back. It looks as if there is a red LED at the top right of the bevelled edge and the unit is designed to plug into either an NTE5/A or a LJU . . . I haven't attempted to deduce the size of the device by measuring the height & width of the 631A plug visible in the image and then scaling appropriately, so I can't be sure if it would fit onto an NTE5/A or one of the earlier LJUs. Also note how it unclips to allow four AA size cells to be fitted. Very mysterious.
Does anyone recognise such a unit, please?
[One other totally irrelevant fact . . . The vendor's address is just a short distance away from where I used to live in the early 1970s.]
It is a 'Phoneguard-P' - a device that locked over the phone socket and used for blocking various outgoing calls. I have one sat in from of me here.