No, you need to physically separate the pairs, you can't just use the filter to do it. When the hub is connected to the master socket, it is a fairly straightforward operation, but by connecting the hub to an extension socket, it makes it more complicated. Does the extension socket you wish to use the phone at daisy chain from the extension socket you use for the hub or from the master socket? If the former, simply disconnect the wires going to the next extension socket and connect those to the hub green socket.
You will either need to fit a BT 431 plug to the cable or use another socket and double ended cord.
if you are currently connected to an extension socket then you now cannot connect your hub to the socket for phone to work. you must isolate the phone connection from the incoming openreach connection used for your broadband
@chrisjp Its a bit messy but it can be done.
At the study you need to provide a second extension socket. Leave pair 1 connected to the original socket for your broadband and then wire pair 2 (which should be spare currently) to terminals 2&5 of the second socket. The second socket is then connected to the hub with the double ended BT431 cord.
At the master socket, disconnect the wires going to the kitchen and connect them to the second pair coming from the study. You can just crimp them together within the master socket.
Hope that makes sense.
This should also improve your broadband speed as it will get rid of the star wiring.
If you have access to the split in the loft, you can simply make the join of pair2 from the study to pair 1 to the kitchen there instead of at the master socket.
Just to clarify – here is the diagram of the telephone wiring
Yep, just do in the loft box what my picture shows in the master socket.