Old Openreach Master Socket

[awaitcall]

Hi
Require some help want to connect an extension telephone wall socket in to my back office.
The openreach master sacket has 4 terminals numbered 1 to 6. Very confusing cuz the numbers dont align up with the terminals. Please see attached photo of the back of master plate.
I will be using cat6 cable please could u put me onto the right direction witch terminals to use

Regards

 

[sparkymarka]

2 and 5

 

[sparkymarka]

Blue / white
White / blue