The master socket has a couple of extra components in it and every house needs to have one master socket then the additional sockets can all be slaves. You could install a master socket anywhere even if it's not going to be used so you could put the master under the stairs or in a cupboard somewhere, it doesn't even need a phone plugged into it. Once there's a master, all the other phone sockets that are visible can then be the modular plate slave sockets.
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc