Yes, a modified Modem.
The Cat 6 cable from the NTE connects directly in to the SamKnows modified modem, into its phone inlet.
Followed by a short Cat 6 cable from adjacent Ethernet port of the SK Modem into the phone inlet of the regular EE Bright Box 2 modem.
That way, all of my traffic, Ethernet and WiFi, is "monitored" and reported by the SK Modem.
I am not aware of any slowing or loading effects of its presence; and as it is "hidden" in a corner, tend to forget its physical presence.
There have been some recent TBB postings about them - particularly if left powered up for months, requiring re-booting - but my one is switched off every night for about 8 hours, so has not caused problems of the reported nature.
The present VDSL SK Modem is basically a white TP-Link device -
Model TL-WR741ND "150Mbps Wireless N Router"
I haven't attempted to access it etc; and there are no obvious signs of it actually being directly active on the WiFi side.
SK sends me a brief report early each month, outlining the BB performance of the immediate previous calendar month, also giving a link to a more detailed version.
The earlier ADSL version, similarly connected etc, was -
CISCO Linksys Wireless-N Broadband Router with Storage Link, Model WRT180NL