This BT phone cable Tripler Adapter can be used to connect three standard BT phone cable devices into one socket. For example, 2 x telephones and a fax machine into a single wall socket
I ordered this item only to receive a double splitter instead of a triple splitter from them. When I sent it back, they then refused to admit their mistake. They also refused to refund me for the P&P.
There are better people to deal on Amazon, avoid this seller.
Need I say more - now my BT line has my router, phone and sky all going into 1 outlet - no need for extensions to be wired round the house (and thus loosing valuable internet speeds through ADSL!)