In reply to a post by MHC:

Have the filter at the master. Then connect the "blue pair" to 2 & 5 which are filtered and they feed the voice socket. Then connect the "brown or green pair" to A&B on the face plate (which are effectively the incoming) and take those to the data socket (RJnn).

Could be a bit tricky anchoring one pair prior to 2 & 5 on the NTE5C and the other pair prior to A&B on the Mk4 plate. Also plenty of outer sheath will need to be removed from the cable since the NTE5C and plate are separate items and the pairs could easily be dislodged/broken from/at the terminals if they are not anchored securely.

It's a much more straightforward job if one had a NTE5 and Mk3 plate where the cable could be anchored only to the plate

if you look at a cat5 socket it you will notice there are indents that are the same size as the rj11, if you have a BT Openreach™ MK3 VDSL you will find you can plug a RJ45 in to the dls socket (VDSL Modem: Direct coupled RJ45 socket (RJ11 compatible))

if you have no need to plug in a phone, you don't actually need a filter of any type, you could just connect the line to the blue/white (pin 4&5) on a cat5/6 faceplate and connect it directly to the router