have just installed 2 slave sockets to a 3 part master socket.
input to Master A and B is blue pair and output comes from back of socket on pins 2 a 5 to first slave and then onto second slave pins 2 and 5 with all polarity correct.
nothing is plugged into master test socket
1st slave has a laptop on broadband
2nd slave has a bankcard swipe card on a normal tel plug and a rj11 feeding a fax -
swipecard and fax work normally
but can only get broadband on disconnecting fax
ie says no dial tone
48 volts present at all sockets - all sockets been changed - fax substittuted
has anyone came across this - installation tests sound except for this clash
these were working in one office with the master and 1 slave