Dunno why you would need any form of amplification. I assume you are trying to distribute one master socket to many places in the house. There is no switchboard type arrangement.
You have also not explained how you have set up your CAT5. Do you have a patch panel?
The way I have done this before is you get a 3 way phone splitter and plug it into the master socket, plug a 2 way into that, you now have space for 4 BT type plugs into your master socket.
Then get a custom made cable that takes the BT wires and sends them to the unused pairs in the CAT5. So the cable has a BT plug at one end and a CAT5 plug at the other end.
Then at the phone end get a CAT5 > RJ11 slave socket widget. PUt that into the cat 5 plug and plug your phone in. Voila.
www.netshop.co.uk supplied the custom cables at 3.66 ea + vat and these
http://www.netshop.co.uk/searchresul...Search=VA258-6
The phone BT631A to three of these can be bought somewhere there or from any Dioxins.
They made my cables up in June 2005. The original cable ref was ZBQTARJSBTP (though I did need to send them back and get them remade).