Cannot find BT master socket to test broadband

Question

House is less than 18months old and had all phone sockets installed prior to moving in as first occupants. BT line connected after 2weeks. Engineer did not enter house. Now have problem with broadband and have been told I need to connect the router to the BT master socket for test purposes but cannot find one! All internal sockets are standard phone sockets.
BT line comes up from ground outside on front wall near door in a BT 'Openreach' box which is a flip-down, secured by a screw. On opening this the BTincoming  connection is sealed, then there is a plug, which if removed disconnects the internal lines. Then there is a connector to which the blue/white/orange leads coming out from through wall from inside the house (white covered cable) are connected. The other side of this wall is underneath the built-in kitchen units and has no master socket anywhere.
Have been banging my head trying to explain to ISP that I cannot connect to a master socket as cant find one. Should I have one or is the outside box all I get? If so, how do I connect the computer to the (6 pin) socket outside?

Answer 1

New build properties are now being fitted with a new Network Terminating Equipment box, the XNTE, instead of the previous NTE5 master socket. This is fitted outside the property and BT responsibility ends at the XNTE. This is the box you referred to with the flip-down cover. It contains all the master socket components. The socket in the XNTE is a BT test point and requires a special plug - it is for BT use only.
In order to eliminate your internal wiring you would need to connect a standard slave socket at the XNTE in place of the white covered cable. Make a note of the way the existing cable is connected. The official connections are pin 2 - Blue, 3 - Brown, 4 - green, 5 - Orange.
See http://www.openreach.co.uk/orpg/networkinfo/developnetwork/downloads/Builders_Guide_3_1.pdf
Peter